HOME, STUDY 



BOTANY 



Highland Park College 



CORRESPONDENCE SCHOOL 



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DELS MOINES, IOWA 



rIE LIBRARY OF 
CONGRESS, 
i M>/o Cowes Received 

SEP, 13 1902 

UOPVRIGHT EKTT*Y 

CL&SS <Z, XXo. No, 
^t 2.733 
COPY B. 



Copyright, 1902, 

BY 

The Highland Park Company 



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BOTANY 



SUGGESTIONS 

1. Plan of work. — In the following lessons in botany 
the plan has been to arrange the topics in accordance with 
the logical development of the science, beginning with the 
simpler forms of plant life and proceeding to the more 
complex. In a few cases it has been found necessary to 
describe the minute structure of some plants, or parts of 
plants, in order that the function of the particular struc- 
ture might be made clear. 

2. Illustrative material. — With the exception of these 
few cases, all the facts given may be studied in connection 
with the actual objects. In no science is laboratory work 
so easy to carry out as in botany, and in none is it more 
necessary. The material for the work is close at hand and 
a large part of it, particularly in elementary work, is of 
such a nature that very little apparatus is needed. A 
sharp, thin-bladed knife and a pocket lens are all the 
apparatus which is necessary for the beginner. 

For those who live in small towns and near the wooded 
districts, the material will not be difficult of access, but 
students living in larger communities may find some 
difficulty in obtaining the proper illustrative material, 
unless they happen to live in the vicinity of a vacant lot 
or two. These, even comparatively large cities possess 
in greater or less number, and it is quite remarkable what 
a wealth of material such a lot will offer. It may contain 
a few trees and shrubs, a vine or two, with some smaller 



2 HOME STUDY — BOTANY 

plants, and here will be found illustrations of bud arrange- 
ment, stem structure, pollination, the light relation, etc. 
If it presents some variations of conditions, such as un- 
even surface, with water supply in varied amount, and 
so on, the study of plant societies may be easily pursued 
on a small scale. For the keen observer and diligent 
searcher, enough material may be found in one such local- 
ity to illustrate many of the fundamental points of botany. 

3. References. — The following are the names of a 
few books of reference which will be of value to those who 
may make use of these lessons. Plant Studies by John 
M. Coulter, of the University of Chicago (D. Appleton 
& Co.) is one of the best of the new texts on general bot- 
any. This book is a combination of two smaller texts, 
each of which may be obtained separately. The first one 
is called Plant Relations and is a study of ecology, and 
the second is entitled Plant Structures. The Foundations 
of Botany by Joseph Y. Bergen (Girm & Co.) and Ele- 
mentary Botany by G. F. Atkinson (Henry Holt & Co.) 
are two other texts intended for high school work. The 
Text Booh of Botany by Drs. Strasburger, ^oll, Schenck, 
and Schimper, of the University of Bonn, translated by 
H. C. Porter (The Macmillan Co.) offers material for 
more advanced study. A very simple, easily understood 
guide for plant analysis is found in the Key to the Flora 
of the Northern United States by Thomas H. Macbride 
of the University of Iowa (Allyn and Bacon). 

Attention is called to the very full index which we have 
provided. By the large number of cross references it is 
made possible to find readily the information sought. We 
know that in their home study our students will appreciate 
the helpfulness of an index which saves valuable time and 
which also greatly enhances the interest of study. 



LESSOX I 

GROUPS OF PLANTS. THALLOPHYTES 

Botany is the science which attempts to answer every 
reasonable question about plants. — Goodale. 

4. Similarity between plants and animals. — There is 
no definite line of distinction between the lower plants 
and lower animals. All differences usually given are 
superficial and erroneous. The statements generally 
made are that plants are unlike animals because they are 
immovable, insensible, are possessed of green color, feed 
upon simple inorganic substances, and have not the power 
of respiration. 

But plants are (1) keenly sensitive to certain condi- 
tions, such as temperature and moisture. (2) They are 
not all immovable ; many lower plants have a translative 
power, while higher plants have power to move certain 
organs. (3) The green color is not found in all plants, 
all the fungi and some others lack it entirely. (4) Some 
plants do live on simple inorganic substances, but the 
fungi are capable of living on very complex organic sub- 
stances which they obtain from decaying materials. (5) 
The respiratory action of plants is very similar to that of 
animals, oxygen being taken in and carbonic acid gas 
thrown off, energy being liberated during the process. 

The fundamental similarity of animals and plants is 
the likeness of the living substance of both, the protoplasm. 

THE PLAXT CELL 

5. The unit of structure. — The cell is the unit of 
plant structure. The bodies of the simplest plants consist 
of but one cell, while the bodies of the most complex 
plants consist of very many^cells. 



HOME STUDY -BOTANY 



6. Parts of a cell. — The usual shape of the cell, if 
free, is spherical. The parts of a cell are (1) the cell 
wall, (2) living substance, the protoplasm, (3) the 
nucleus, (4) cell sap. 

(1) The cell wall is a thin jacket around the cell, made 
of a substance called cellulose. 

(2) The protoplasm is a semifluid substance which is 
in appearance and thickness much like the white of an 
egg. When seen in the living plant it is in constant mo- 
tion in the cell, traveling up one side and down the other. 
It has many properties: 

(a) It has the power to take up new materials into its 
own substance. This is not merely of soaking up liquids, 
but the selection of some substances and rejection of others. 
This is selective absorption. 

(b) It has power to change certain substances into others 
of different chemical composition. This is metabolism. 

(c) It has the power to cast off waste materials. 

(d) It has capacity for growth and reproduction. These 
are especially characteristic of active protoplasm. 

(e) It is sensitive when touched or otherwise disturbed, 
as by a change of light or temperature. 

(3) The nucleus is a 
thickened portion of the 
protoplasm. It is the most 
important part of the cell. 
That part of the proto- 
plasm outside the nucleus 
is called the cytoplasm. 



A*~ 



B 



C ■ 




Fig. 1. Cells from a moss leaf, showing 
nucleus (B) in which there is a nucle- 
olus, cytoplasm (C), and chloroplasts 
(A). — Caldwell. 

From Coulter's Plant Structure?. 
Copyright, 1899, by D. Appleton & Co. 



(4) The plant cell is 
not filled with protoplasm, 
but has a lining of it and 
inside of this is the cell 
sap, which is water hold- 
ing in solution the food 
elements required by the 
plant, either in a crude or 
elaborated form. 



GROUPS OF PLANTS— THALLOPHYTES 5 

THE GREAT GROUPS OF PLANTS 

Even the casual observer will note that plants differ 
very much in structure. Some are simple, others com- 
plex, and the former are regarded as of lower rank. 

7. Names of groups.— Four great groups of plants are 
known, each group representing certain stages in the 
gradation from lower to higher rank. The names of the 
groups are : 

(1) Thalloplrytes. — The name means thallus plants. 
In this group are included some of the simplest forms, the 
algae and the fungi. 

(2) Bryophytes. — The name means moss plants. Here 
are placed the liverworts and the mosses. 

(3) Pteridophytes. — Fern plants. Here are placed the 
ferns, club-mosses, and horsetail rushes. 

(4) Spermatophytes. — Seed plants. These last are our 
most familiar plants and are commonly spoken of as 
flowering plants. They are highest in rank and most con- 
spicuous and hence have received much attention. 

S. Cryptogams. — The Thallophytes, Bryophytes, and. 
Pteridophytes are often classed together under the term 
Cryptogams, which means that they are all flowerless 
plants. Nearly all of them, excepting only the simpler 
forms, reproduce by means of a body called a spore. A 
spore is a single cell set aside for the purpose of reproduc- 
tion ; a much simpler form of reproduction than a seed. 

Spores are produced in two ways, either (1) asexually, 
from the protoplasm of some part of the plant, or (2) 
sexually, by the combination of two sex elements, two 
masses of protoplasm from two separate plants or from 
different parts of the same plant. 

9. The evolution of plants.— It is generally supposed 
that the more complex plants have descended from the 
simpler ones, that the Bryophytes have been derived from 
Thallophytes, and so on. All the groups, therefore are 
supposed to be related in some way. This theory of the 
relationship of plant groups is known as evolution. To 



6 



HOME STUDY — BOTANY 



well understand any higher group one must study the 

lower ones related to it. We present a careful study of 
some types of the subgroups. 



THAILOPHTTES 

10. Algse. — Alga? are generally denned (1) as plants 
■ >ssessing a ihallus. which is a vegetative or nutritive 
body, having neither true root, stem, nor leaves ; and i 2 I 
as possessing chlorophyll, which is the green coloring mat- 
ter of plants. Algae are found in water or damp places. 




Fig. 6. Plei/rococci/s. a one-celled green alga : A. show- 
ing the adult form with its nucleus ; B. C. D. E, 
various stages of division (fission) in producing new 
cells ; F. colonies of cells which have remained in 
contact. — C axdweix. 
From Coulter's Plant Structures. Copyright, 1899. by D. Appleton & Co. 

11. • Pleurococcus. — This is a one-celled alga plant. It 
is commonly found in masses covering damp tree trunks 
and on the sides of buildings in damp localities, and looks 
like a green stain. These masses are made up of multi- 
tudes of spherical cells, which may be solitary or may 
cling together in groups. The finely granular green por- 
tion of each cell is the chlorophyll. In this plant we have 
illustrated the simplest form of reproduction of plant 
bodies, cell division. Each cell divides and forms two 
new cells, each of the two forms two others, and so on. 



GROUPS OF PLANTS-THALLOPHYTES < 

1*2. Spirogyra. — This is one of the commonest of algse. 
It is found in ponds, slow running streams, and in water- 
ing troughs. It may bo recognized by its threadlike struc- 
ture, brilliant green color, and slippery feeling. 

Each of the threadlike portions or filaments is made 
up of a number of cells, joined end to end. In the cells 
are remarkable chloroplasts, or chlorophyll bearing bodies, 
which are bands passing spirally around the cell. 

In its life history spirogyra represents the beginnings 
of reproduction by sex elements, or gametes, as they are 
called. Two filaments lying side by side, put out tubular 
processes toward one another. When the tips of two such 
processes come together, the end walls disappear, and a 
continuous tube extending between the two cells is formed. 




Fig. 14. Spirogyra, showing conjugation : A, conjugating tubes approaching each 
other; B, tubes in contact but end walls not absorbed: C, tube complete and con- 
tents of one cell passing through; I), a completed zygospore. — Caldwell. 

From Coulter's Plant Structures. Cop\ right, 1899, by D. Appleton & Co. 



8 HOME STUDY — BOTANY 

While the connecting tube is being developed, the con- 
tents of the two cells thus being united are organizing, and 
after the completion of the tube, the contents of one cell 
pass through and enter the other cell, fuse with, its con- 
tents and a sexual spore is formed. This spore is well 
adapted to withstand changes in seasons, and is in reality 
a resting spore. At the beginning of each growing sea- 
son, the resting spores germinate directly into new 
spirogyra filaments. 

13. Other forms of algae. — Many other forms of alga? 
exist. The two forms described belong to the green alga?. 
The other great alga groups are the blue-green, the red, 
and the brown alga?. In the last three groups, chlorophyll 
is present, but is masked by other coloring substances in 
the plant. The green and blue-green alga? are character- 
istic of fresh water, but the red and brown alga? are found, 
with a few exceptions, in salt water. The beautiful sea 
weeds of our roasts belong to these groups. 

14. Fungi. — In general, the fungi are Thallophytes 
which do not possess chlorophyll. As chlorophyll is the 
element by means of which the plant is enabled to manu- 
facture its food, it follows that these plants cannot manu- 
facture food out of inorganic material, but are dependent 
for it upon other plants, or upon animals. This food is 
obtained in two ways, either (1) directly from the living 
bodies of plants or animals, or (2) from dead bodies or 
the products of living bodies. Those which belong to the 
first class are called parasites, and the plant or animal 
class are called saprophytes. 

Some fungi can live only as saprophytes, or as parasites, 
but some can live in either way. 

15. Economic value of fungi. — The fungi are much 
more numerous than the alga?. Many of the parasites 
attack and injure useful plants and animals, producing 
many of the so-called diseases and so are objects of great 
interest. Xot all of the fungi, however, are harmful, 
many of the parasitic forms being harmless, while many 
of the saprophytic forms are decidedly beneficial. 



GROUPS OF PLANTS— THALLOPHYTES 

16. Plan of structure. — Setting aside certain forms, 
such as yeast and bacteria, the bodies of all true fungi are 
organized upon a general plan. The main part of the 
plant consists of a mass of branching filaments, called the 
mycelium. This may be a loosely interwoven mass; or it 
may be close and compact, forming a feltlike mass, as may 
often be seen in the mould upon preserved fruits. This 
mycelium is in contact with the source of food supply. 
The threads of the mycelium are known as hyphae (singu- 
lar hypha). Those which are vertical, are set apart to 
produce the asexual spores, which are scattered and pro- 
duce new mycelia. These branches are called ascending 
hypha?. 




Fig. 32. A diagrammatic representation of Mvcor, showing the profusely branching 
mycelium, and three vertical hyphae (sporophores), sporangia forming on b and c. 
— After Zopf. 



From Coulter's Plant Structures. Copyright, 1899, by D. Appleton & C< . 

17. Black mould. — This is one of the most common 
of the fungi and may be found growing in abundance 0:1 



10 HOME STUDY- BOTANY 

decaying fruits or vegetables, on damp bread, or on manure 
heaps. 

On mouldy bread the slender, threadlike network of the 
myeeliuni may be seen with the naked eye. or with a 
simple hand lens. The delicate threads, arising at inter- 
vals from the mycelium, are the ascending hypha?. On 
the tips of these are found tiny black dots. These little 
spheres are the sporangia or spore cases, each a transpar- 
ent sac packed full of black spores. The reproduction is 
1 rought about by means of the spores, which are scattered 
through the air when the sac is ruptured, and which., when 
they light upon some organic matter, grow, producing 
new myeelia. 

1 8. Chemical action.— When mould acts upon any sub- 
stance, such as bread, that substance is consumed by the 
mould. The bread shows this bv its change in taste, oivino- 
evidence of chemical change undergone in its sub-tanee. 
In canned fruit, if the process continues for a long time, 
little is left but water. 

19. Mushrooms and puffballs. — This group includes 
also the toadstools, which are not botanically distinct from 
mushrooms. These are the most highly organized of the 
fungi. They are not destructive parasites, but mostly 
harmless and often useful saprophytes. 

20. Mushrooms. — A common mushroom consists of a 
mycelium of white branching threads, spreading exten- 
sivelv through the substratum of deeavins: leaves and 
grass. Upon this mycelium little buttonlike knobs begin 
t<» arise, growing larger and larger until they are formed 
into the part which we call the mushroom, and which is 
simply the fruiting portion of the plant. The mushroom 
is composed of two parts, the stalklike portion or stipe, 
and the expanded cap or pile us. On the under surface of 
the pileus hang great numbers of "plates or gills, radiating 
from the center. Each gill is a compact mass of hypha?. 
whose tips bear the spores by means of which the plant is 
reproduced. 



GROUPS OF PLANTS-THALLOPHYTES 1 1 

21. Puffballs. — The puffballs have their fruiting por- 
tion in the form of globular bodies, within which I lie 
spores develop and which are set free only when ripe. 

22. Bracket fungus. — Another form of this division 
of the fungi is found in the bracket or shelf fungus, which 
forms shell-like outgrowths on tree trunks, stumps, and 
posts. 

23. Rusts, mildews, and smuts. — These groups may 
be illustrated by the fungus attacking wheat, producing 
the wheat rust, the fungus attacking the grape, producing 
grape mildew, and the one attacking corn, producing corn 
smut. The rust } mildew, and smut represent mainly the 
fruiting portion of tile plant, being accumulations of 
spores and spore-bearing portions. The hyphre of these 
forms penetrate the tissues, causing in many cases vast 
injury to the plant. So these are among the most harm- 
ful of the parasitic fungi. 

All of these forms have very complicated and obscure 
life histories, and no indication of a sexual process of 
reproduction has been noted in them. 

2-1. Yeast. — Yeast is a one-celled fungus plant, of 
microscopic size. In its wild form it is found in the 
ground around apple trees, grapevines, etc. The form 
which is of economic importance is a cultivated plant. 
Yeast will grow only in solutions containing sugar. The 
presence of yeast in a substance may be determined by 
the bubbles of gas arising from the liquid, by the sharp 
odor due to the presence of alcohol, and by the yellovdsh 
sediment. 

25. Fermentation.' — In performing its functions yeast 
brings about fermentation in substances. Fermentation 
is the changing of sugar to alcohol and a gas called carbon 
dioxide. The gas is liberated from the mixture in the 
form of bubbles, and the alcohol remains in the liquid. 
When yeast acts upon the juices of certain plants which 
contain sugar various alcoholic liquors, as wine and 
whisky, are formed. 







V » 







Fig 68. A group of Bacteria, the bodies being black, and bearing motile cilia in 
various ways. A, the two to the left the common hay Bacillus (B. subtiBs), the 
one to the right a Spirillum ; B. a Coccus form (Pla?wcoceus^: C, J). E. species of 
Psevdomonas : F. G, species of Bacillus. F being that of typhoid fever: H. Iticro- 
spira ; J, K, L, AT, species of Spirillum.— After Engler and Prantl. 

From Coulter's Plant Structures. Copyright, 1899. byD. Appleton & Co. 



'groups of plants-thallophytes 13 

2<>. Bread making. — In bread making, yeast acts upon 
the sugar present in the grains, and causes the formation 
of carbon dioxide and alcohol. Wheat flour contains a 
large amount of a substance called gluten, which is very 
sticky, and serves to make cavities in which the gas is 
imprisoned, thus causing the lightness of the bread. When 
baked all the yeast plants are killed and the alcohol is 
evaporated by the action of the heat of the oven, thus leav- 
ing a wholesome product. 

The growth of the yeast plant is promoted by a mod- 
erate degree of warmth, and by the proper per cent of 
sugar. It cannot grow in pure water or in pure syrup. 

-7. Bacteria. — The bacteria form one of the impor- 
tant groups of the fungi. They are remarkable because of 
their extreme minuteness and of their extraordinarv 
power of multiplication. 

They are the smallest known living organisms, and 
multiply by cell division with wonderful rapidity. They 
also form resting spores for distribution and preservation. 
They occur everywhere, in the air, in the water, in the 
soil, in the bodies of animals and plants. Many of them 
are harmless, many of them useful, and many of them 
dangerous. 

They are of various forms, as bacilli forms, short rod 
shaped cells, spirillum forms, spiral filaments, cocci forms, 
in shape of spheres, and the like. 

28. Bacteria as agents of decay. — Under the head of 
beneficial effects of bacteria may be stated their work in 
producing decay in the tissues of dead animals and plants. 
If it were not for the destructive action of these bacteria, 
all the food materials needed by other organisms would be 
locked up in the form of dead tissues to cumber the earth, 
ami after all the available material had been thus locked 
up, there could be no food supply for plants and animals. 

29. As agents of nitrogen fixation. — Bacteria are 
beneficial also in enriching the soil that lacks nitrogen, an 
element which plants must have for their food, and which, 
although it exists in great quantities in the air, they are 



14 HOME STUDY — BOTANY 

not capable of using, except as it is found in solution in 
the water which they obtain f roni the soil. Certain plants, 
as the clover, bean, and pea, together with other plants 
belonging to the order legumvnosm, have attached to then- 
roots colonies of bacteria, and these bacteria have the 
power to take nitrogen from the air contained in the soil, 
and to fix it in their own bodies. When they die and 
decay, the plant to which they are attached can make use 
of the nitrogen. During this time the bacteria are doubt- 
less obtaining food from the roots of the plant, but with- 
out api^arently injuring it. 

This habit of clover and its allies explains why they are 
useful in what is called restoring tlxe soil. After ordinary 
plants have used all the nitrogen containing salts, and 
the soil has become somewhat sterile, clover can grow upon 
it bv obtaining its nitrogen from the air through the aid 
of the bacteria. If the clover is plowed under the decay 
of the plants gives to the soil the nitrogen necessary for 
the growth of other plants. The presence of the bacteria 
upon the roots of the clover and allied plants is indicated 
bv tubercles, which are excrescent growths caused by the 
bacteria. 

30. Bacteria and cheese. — One of the minor points in 
which bacteria are useful is in producing the flavor of 
cheese. Each particular variety of cheese owes its flavor 
to a certain class of the bacteria, which develops in its 
substance during the ripening process. Many varieties 
of cheese can be produced only in certain localities, favor- 
able to the particular bacteria which produce their flavors. 
Some of the foreign varieties of cheese, however, are now 
produced in America, by taking the imported cheeses and 
rubbing the shelves of the ripening rooms with them, by 
which means the bacteria obtain a foothold for growth. 

31. Bacteria and disease. — The pathogenic forms, 
that is, those which produce diseases of plants and of ani- 
mals, are of great importance, and means of making them 
harmless or destroying them are being searched for con- 
stantly. These are the parasitic forms, and one or two 



GROUPS OF PLANTS-THALLOPHYTES 



15 



examples will serve to illustrate how they find a lodgment 
in the host. 

Sewage water often swarms with the baeillns of typhoid 
fever. The people in the city drink urn-filtered water into 
which sewage has been allowed to run higher up the 
stream, the bacilli multiply at a rapid rate in the intes- 
tines of those who have drunk the water, and many of 
them are taken sick with typhoid fever. Also, the phlegm 




Fig. 72. Section through thallus of a lichen (Sticta), showing holdfasts (r), lower (u) 
and upper (o) surfaces, fungus hyphse (m), and enmeshed algae (g). — After Sachs. 

From Coulter's Plant Structures, Copyright, 1899, by D. Appleton & Co. 

exjDectorated by consumptive patients is full of the con- 
sumption bacillus. This phlegm becomes dried on floors, 
streets, or sidewalks, it is breathed by everyone in the 
form of fine dust, and in the lungs of many who breathe 
it, colonies of harmful bacilli are formed and thus the 
disease becomes established in these persons. . 

The diseases caused by bacteria are not a result of the 
presence of the bacteria in the body, but of the destructive 



16 HOME STUDY — BOTANY 

effect of certain bacteria upon the tissues, producing 
poisons called toxins. These poisons, it is inferred from 
certain experiments, are neutralized by certain antitoxins 
which the blood has the power of forming. The produc- 
tion of the antitoxin is thus apparently a distinct reaction 
of the body to the stimulus of the toxin in such a way as 
to neutralize its bad effect, provided the vitality of the 
tissues has not been already too far lowered by an over- 
whelming amount of toxin. 

32. Lichens. — Lichens are abundant everywhere, 
forming various colored spots on the trunks of trees, rocks, 
and old boards, and growing also upon the ground. They 
have a general grayish color, but brighter colors may also 
be observed. Some are possessed of a leafy structure, 
others grow as if they formed part of the bark or rock to 
which they are attached. 

The great interest connected with lichens is that they 
are not single plants, but each lichen is formed of a fungus 
and an alga, living together so intimately as to appear like 
a single plant. The fungus makes the bulk of the body, 
with its interwoven mycelial threads in the meshes of 
which lie the one-celled alga plants. 

These two plants are thought by some to be mutually 
helpful, the alga manufacturing food for the fungus, and 
the fungus providing protection and water containing food 
materials for the alga. Others do not recognize any spe- 
cial benefit to the alga, but see in a lichen simply a para- 
sitic fungus living upon the products of an alga. In any 
event, the algse are not destroyed but seem to thrive. 

QUESTIONS 

1. In what ways are plants and animals similar ? 

2. Upon what is the fundamental similarity of plants 
and animals based ? 

3. What is a cell ? What are the parts of a cell ? 

4. What is protoplasm ? What are its most impor- 
tant properties ? 



GROUPS OF PLANTS-THALLOPHYTES 17 

5. What is the nucleus ? Cytoplasm? Cell sap? 

6. What does the picture on page 4 show ? 

7. What are the great groups of plants ? 

S. What are cryptogams \ How do the cryptogams 
reproduce \ What is a spore ? 

9. What is meant by the evolution of plants ? 

10. What are algae? Where is pleurococcus found? 
What is its appearance \ How does it reproduce ? 

11. What is the leading purpose of the picture on page 
6? 

12. Where is spirogyra found? How does it repro- 
duce \ 

13. What distinct steps are illustrated in the picture 
on page 7 ? 

14. What are some of the other forms of algse ? Where 
f ound ? 

15. What is chlorophyll? Why is its presence some- 
times not apparent ? 

16. What are fungi ? How do they obtain their food? 
Why do they not obtain it in the same manner as the 
alga? ? What is a parasite ? A saprophyte ? 

17. What is the general plan upon which most of the 
true fungi are organized ? What plants of this group are 
exceptions to this plan ? 

18. From the picture on page 9 do you get a clear 
idea of the sporangia ? 

19. What is black mould ? Where found ? How does 
it reproduce ? What are sporangia ? 

20. Describe a common mushroom. How do mush- 
rooms reproduce ? What is the toadstool ? 

21. What are puffballs ? What are bracket fungi ? 

22. What are rusts, mildews, and smuts? What is the 
economic importance of this class of the fungi ? 

23. What is yeast ? How is its presence in a substance 
determined ? What is fermentation ? How is wine made ? 
What is the use of yeast in bread making ? What condi- 
tions are necessary for the growth of the yeast plant ? 



1 s HOME STUDY — BOTANY 

24. What are bacteria? What is said of their size 1 
How do they reproduce '. What are resting sp:»res and 
why do the bacteria form them i 

25. What does a careful study of the picture of page 
li' ■..is:--: -r : 

i S. Where are bacteria found i What are some of the 
forms they exhibit -. 

1 7. What are some of the beneficial effects of bacter: ! 
What is the necessity of decay '-. Why does clover restore 
the soil of a field in which it srrows '. 

i - . In what wav are bacteria harmful \ How do thev 
find lodgment in their hosts \ 

29. To what are the diseases caused by bacteria due ! 
What are toxins ' WJiat are antitoxins { 

30. What are lichens '. Where found l Of what is a 
lichen composed \ What is the probable significance of 
the two plant forms thus unite : 

31. Do you derive a good impression of the holdfasts, 
the fungus hyphae. and the enmeshed alga?, shown in the 
picture on page 1 ■ : 

i . Why is it desirable to boil drinking wate: : 

Why are foods preserved by cauuizii i 
-. Why is cold storage a means of food preservation? 
Why will mould not grow on clean sand or in pure 
wate: : 

36. Why does mould grow on bread and fruit ' Why 
does it not have chlorophyll '. 

7. Lichens are often found growing on a tree. Do 
they damage the tree ' Why not 1 

35. Why do mushrooms and other fungi expose to the 
air their spore bearing portion- \ 



' LESSOX II 

BRYOPHYTES. PTERIDOPHYTES. BUDS 

33. Classes of Bryophytes. — Under this head are 
classed the liverworts and the mosses. Both of these classes 
consist of plants much more highly organized than the 
Thallopytes. Bryophytes have no true roots, bnt have 
organs which perform the work of roots. Some of them 
have leaves, while others have none. They have no true 
woody structure, such as is found in plants of still higher 
groups. There are chlorophyll bodies present in all of 
them. 

34. Reproduction. — Reproduction is of two kinds, 
sexual and asexual, and the organs by which it is carried 
on are complicated and highly organized. In the life his- 
tory of each class there is exhibited what is known as alter- 
nation of generations. That is, each plant during its life 
cycle really has two different forms ; one which is produced 
by the union of two sex elements or gametes, and one which 
arises from an asexual spore. This asexual spore is pro- 
duced by the plant which arises from the sexual union. 

35. Liverworts. — Liverworts live in a variety of con- 
ditions, some floating on the water, majiy in damp places, 
and many on the barks of trees. There are three great 
classes of liverworts, but the species are numerous in only 
the first two classes. The one which will be described 
belongs to the first class, but to the second in importance, 
from the standpoint of the number of species. 

36. Marchantia polymorpha. — This is one of the most 
common and familiar of the liverworts. It is a flat, 
ribbon-like, green little plant, found commonly creeping 



i ; :-: : :-iz szv: v-z izany 

:~zr n::«:. cool soil in shady places. It is also common 



body consists of a flattened leaf -like portion, 
th its green color sliffhthr darker above than 




. _ . _ ■ * 



5t7v:tv7Z= Z::-::: l!>- :j - 



The npper surf ace is marked off in diamond 
ureas, and in the center of each is a minute open- 
l oma (plural stomata). Along the under surface 



BRYOPHYTES-PTERIDOPHYTES-BUDS 21 

of the thallus are root-like structures called rhizoids, 
which attach the plant to the substratum. 

On the upper surface of the thallus are found conspic- 
uous shallow cups, in which lie small green bodies visible 
to the naked eye. The cups are called cupules, their con- 
tents, gemmae. These gemmae are simply buds, and a drop 
of water is sufficient to float them from the cupules. Once 
they find lodgment on suitable soil, each one is capable of 
developing a new plant. 

On some of the portions of thallus are found very differ- 
ent sorts of structures. These are of two kinds, and are 
the reproductive bodies concerned in the sexual reproduc- 
tion. One has a short stalk and a concave, disc-like top 
with crenulated edges. This is called the antheridial disc, 
and has in it numerous minute sacs called antheridia, in 
which the fertilizing cells are developed. These fertiliz- 
ing cells are called spermatozoids and are the male or fer- 
tilizing elements. They are single cells, bearing a num- 
ber of hair-like processes on the end, by means of which 
they are enabled to move through water. 

The other reproductive body has a somewhat longer 
stalk, and a star-shaped or radiate disc. This is called the 
archegonial disc. On the under surface of the rays of 
this disc are found little flask-shaped bodies, placed with 
the neck downward, and these are called archegonia. These 
archegonia contain the female element, the oosphere, 
which awaits fertilization. 

The process of fertilization is as follows : In April or 
May the antheridial cells have their walls upturned, and 
the spermatozoids escape and swim to the archegonial 
discs. They are so minute that dew or any small amount 
of water will furnish sufficient water for their passage. 
They are supposed to be directed in their course by chem- 
ical attraction between them and the female cell. Reach- 
ing the archegonial disc, they pass into the neck of the 
archegonium, and unite with the oosphere, producing a 
single cell called an oospore. From this oospore is devel- 
oped by cell division, a sporogonium, a type of spore case 



22 HOME STUDY — BOTANY 

peculiar to Bryopkytes. This sporogonium contains 
besides a great number of spores, a number of threads 
called elaters. These are delicate thread-like organs, 
which twist and squirm under the influence of moisture, 
and help to scatter the spores. 

The alternation of generations is as follows : The spore 
gives rise to the thallns which bears the branches, this is 
one generation, the oospore gives rise to the sporogonium, 
with its spores, the second generation. That alternation 
of generations is of great advantage is evidenced by the 
fact that it appears in all the higher plants. It does not 
really commence in the Bryophytes, but its beginnings 
may be seen in the Thallophytes. The full benefit of this 
alternation of generations is not known, but one advantage 
seems prominent, and that is, that by this means the prod- 
uct of the sexual spore is multiplied, and thus gives the 
species a Fetter chance in the struggle for existence. 

It is plain that if there were no alternation of genera- 
tions, each sexual spore would produce but a single plant, 
but through the agency of this alternation many sexual 
spores are produced, each of which may give rise to a new 
individual. 

37. Mosses. — Mosses are highly specialized plants, 
probably derived from liverworts, the numerous forms 
being adapted to all conditions from submerged to very 
dry, being found most abundantly in the temperate and 
arctic regions. 

They have the power of reproduction by simple multi- 
plication of the vegetative portion of the plant, new leafy 
shoots putting out from old ones indefinitely, forming- 
thick masses. Certain forms thus completely fill up bogs 
or small ponds with a dense growth, which dies below and 
continues growth above so long as conditions are favorable. 
The lower layers of the moss in these bogs, instead of 
decaying, become modified into a coaly substance called 
peat. 

The spore in the case of the moss plant, instead of devel- 
oping a thallus, sends out a thread-like structure, made 



BRYOPHVTES - PTERIDOPH VTES - BUDS 



23 



up of chlorophyll bearing colls, and which branches again 
and again until a dense felt-like mass, covering consider- 
able space, is formed. This is the protonema or first 
Hi read, and corresponds to the thallus of the liverwort. 
Upon this protonema, at intervals, are produced buds 
which give rise to the moss plants. These are erect, hav- 
ing rhizoids to hold them in the soil, and bearing leaves 
which are arranged about a central stem. The archegonia 




Fig. 81. Protonema of moss: A, very young protonema, showing spore (S) which 
has germinated it; B, older protonema, showing branching habit, remains of 
spore (s), rhizoids (r), and buds (b) of leafy branches (gametophores). — After 
Duller and Thurgau. 

From Coulter's Plant Structures. Copyright, 1899, by D. Appleton & Co. 

and antheridia are produced in little rosettes of leaves at 
the top of the stems of the plants, and the process of repro- 
duction is similar to that of the liverworts. 

In the mosses, however, the oospore gives rise to a some- 
what different form of sporogonium. From the leafy 
rosette a long stem is sent out, which bears on its tip an 
oval body called a capsule, having a lid by which it opens. 
This capsule contains the spores. There are no elaters 
present in mosses. On some of the common mosses a little 



24: HOME STUDY — BOTANY 

cap, which is the remains of the old archegonium, in which 
the fertilizing cell was borne, is found fitting over the 
capsule. When the lid of the capsule falls off, a circle of 
tooth-like structures is seen around the mouth of the cap- 
sule. These teeth are susceptible to changes in moisture, 
and by bending backward and forward under the influence 
of these changes, help the spores to escape. 

PTEKIDOPHYTES 

38. The ferns. — The ferns are the most numerous and 
most representative of this group. They well deserve to 
stand as types, for they contain about four thousand of the 
four thousand five hundred species belonging to the 
Pteridophytes. Although found in considerable number 
in the temperate regions, their chief display is in the trop- 
ics, where they form a striking and characteristic feature 
of the vegetation. Many of the low forms are to be seen 
in the tropics, and also tree forms with trunks rising to a 
height of thirty-five to forty-five feet, bearing leaves fif- 
teen to twenty feet long. 

39. Horsetail rushes and club-mosses. — Associated 
with them, are the horsetails (scouring-rushes) and club- 
mosses. The horsetails are represented by but a few 
forms, and their jointed stems and harsh texture have 
made them familiar objects to many. The club-mosses 
are represented by a greater number of forms, one group 
of forms, selaginella, being found in greenhouses as deli- 
cate, decorative plants, another called lycopodium fur- 
nishing our Christmas greens. 

Both horsetails and club-mosses are representatives of 
groups which were very abundant during the coal meas- 
ures, and helped to form the forest vegetation. 

40. Appearance of the vascular system. — One of the 
most important facts in connection with the Pteridophytes 
is the appearance of a vascular system, which is a system 
of vessels forming the woody tissue of the plant, and 
organized for conducting material through the plant body. 



BRYOPHYTES-PTERIDOPHYTES- BUDS 



25 



The appearance of this system is of as much importance 
in the plant kingdom, as is the appearance of a backbone 
in the evolution of animals. As animals are classed as 
vertebrates and invertebrates, so plants are grouped as vas- 
cular and non-vascular, the former being the Pteridophytes 
and Spermatophytes, the latter being the Thallophytes 
and Bryophytes. 

Alternation of generations continues in the Pteri- 
dophytes, but is even more distinct than in the Bryophytes. 
This can be shown by a study of the life history of any 
common fern. 




Fig. 111. Prothallium of a common fern (Aspidium); A, ventral surface, showing 
rhizoids (rh), antheridia (an), and archegonia (ar) ; JB, ventral surface of an older 
gametophyte, showing rhizoids (rh) and young sporophyte with root (w) and leaf 
(6). — After Schenck. 

From Coulter's Plant Structures. Copyright 1899, by D. Appelton & Co. 

4:1. Study of the common fern. — On the back of the 
leaves of ferns, at the fruiting season, are found dark spots 
or lines. These yield spores. When one of these spores 
germinates it gives rise to a small, green, heart-shaped 
thallus. This is called the prothallium, and is often a 
quarter of an inch or more in diameter. These can often be 
found growing on the surface of the soil in pots of green- 
house ferns. Upon this prothallium the antheridia and 



HOME STUDY — BOTANY 

archegonia appear, the sperniatozoids are liberated a? in 
the liverworts and mosses, and enter the archegonia. fuse 
with the oosphere and form the oospore. \Yhen this oospore 
germinates it develops the large leafy plant ordinarily 
spoken of as the fern, with its subterranean stem from 
which the roots descend. It is in this complex body that 
the vascular system appears. 

Each leafy portion of the fern is called a frond, and the 
subdivisions are pinnae (singular pinna). On the under 
side of the pinnae the fruit dots or sori (singular sorus) 
are found. 

Each sorus is composed of a number of sporangia and a 
little membranous covering called the indusium. In the 
common brake fern (pteris) and in the maidenhair there is 
no indusium, but the sporangia are covered by the incurved 
edge of the fronds. 

Each sporangium is a little oval body, borne on a stalk, 
and having a special apparatus for the distribution of the 
spores, and these spores in turn give rise to new prothallia. 

Two facts are characteristic of ferns, one is the manner 
of branching of the veins in the frond, the peculiar forked 
character of the veining being very conspicuous, the other 
is the manner in which the leaves in expanding seem to 
unroll from the base, as though they had been rolled from 
the tip downward. This habit is spoken of as circinate, 
from a word meaning circle or coil. 

SPEBMATOPHYTES 

±2. Importance of the group. — This group has often 
been studied alone as botany, to the exclusion of the other 
groups. This is because they are most conspicuous of all 
plants, and because they are greater in number and display 
than the other groups. The lower groups must be studied. 
not only to give a general view of the plant kingdom, but 
because a knowledge of their structure and functions is 
essential to an understanding of the structures of the high- 
est group. 




Fig. 118. A fern (Aspidium), showing three large branching leaves coming from a 
horizontal subterranean stem (rootstock); young leaves are also shown, which 
6how circinate vernation. The stem, young leaves, and petioles of the large 
leaves are thickly covered with protecting hairs. The stem gives rise to numerous 
small roots from its lower surface. The figure marked 3 represents the under sur- 
face of a portion of the leaf, showing seven sori with shield-like indnsia; at 5 is 
represented a section through a sorus. showing the sporangia attached and pro- 
tected by the indusium; while at 6 is represented a single sporangium opening 
and discharging its spores, the heavy annulus extending along the back and over 
the top. — After Wossidlo. 



From Coulter's Plant Structures. Copyright, 1899, by D. Appleton & Co 



28 HOME STUDY — BOTANY 

The plants of this group are called Spermatophytes 
(seed plants) because the most distinguishing niark of the 
group seems to be the production of seeds. These plants 
follow the Pteridojxhytes without any sharply defined 
barrier, representing of course more highly deYeloped 
forms. Their more adYanced deYelopment is limited to 
the asexual generation, the plant body as a whole being in 
this stage, while the sexual generation has been reduced 
to a few cells found in the seed, and dependent upon the 
other generation for existence. This change in the rela- 
tion between the two generations has been brought about 
gradually. Through successive stages from lower to 
higher forms the asexual generation, which at first was of 
smaller size, becomes the larger, and the reverse is true of 
the sexual generation. 

The reproduction of this class of plants will be better 
understood after some study of the flower and the other 
characteristic organs. 

BUDS 

43. Dissimilarity of trees. — Comparing a number of 
twigs from different trees, such as elm, soft maple, box 
elder, oak, apple, cherry and others, a great dissimilarity 
will be noticed. This unlikeliness is due to various pecul- 
iarities, such as the character of the bark, the buds, and the 
development or suppression of branches. With very little 
study, it may be made clear that trees can be distinguished 
by their branches alone, without leaves, flowers, or fruit. 
The study of the tree in its winter aspect is of great 
interest. 

44. Bud arrangement. — Taking a single twig, as the 
box elder, there may be seen peculiar crescent-shaped 
markings, uniting to form a ring, generally lighter in color 
than the rest of the twig, occurring at comparatively reg- 
ular intervals, and becoming more distinct toward the tip. 
These are the leaf scars, and each marks the place of one 
of the last year's leaves. That part of the stem which 



BRYOPHYTES— PTERIDOPHYTES- BUDS 29 

bears the leaf (two in this case, sometimes more or fewer) 
is called the node and the space between two successive 
nodes is the intemode. The internodes become shorter 
toward the tip of the stem. 

The buds are arranged one above each leaf scar, oppo- 
site each other and therefore in pairs up and down the 
stem. Each twig if uninjured terminates in a bud. This 
is the terminal bud, distinguished thus from all the others, 
which together are called axillary buds. This latter term 
results also from the position of the bud, each one being 
borne in the axil of a leaf, which is the angle inclosed 
between the upper side of a leaf and the stem upon which 
it is borne. This may be made clear by looking at twig's 
just before the fall of the leaves in autumn, and noting the 
position of the bud which has been formed during the 
summer's growth and which will remain upon the twig 
after the leaf has fallen. 

If we look now at a twig from the elm, some differences 
may be noted. The leaf scars are present, and nodes and 
internodes may be distinguished as before, but here onlv 
one bud will be found at a node, and the ones at successive 
nodes will be on opposite sides of the stem. This is called 
the alternate arrangement of buds, while that of the box 
elder is known as the opposite arrangement. 

Looking at twigs from many trees and shrubs it will be 
found that the greater number of them can be grouped 
under the one or other of these two classes of bud arrange- 
ment. The exceptions would be in the case of a few 
plants whose stems would bear more than two buds at a 
node, in which case the arrangement is said to be whorled. 
The catalpa is an example of this arrangement. 

45. Structure of a bud. — Tor the study of the 
structure of a bud, the lilac offers good material. Taking 
a single bud and cutting it across, little pairs of undevel- 
oped leaves and brown scales may be found packed away 
in it. With a needle point the brown scales may be 
picked away from the outer part, and they will be found 
to be hard, while the little green leaves inside are soft. 



30 HOME STUDY— BOTANY 

These may be picked away, until only a little greezi sT^i-i 
or core is left 

If buds tli at bare been growing for some time may now 
be obtained, it Trill be seen that growth consists in the 
lengthening of this little core into a stem, upon which are 
borne the new leaves. The bud scales which covered these 
portions will have disappeared, or some of them may still 
}ye found in a chaster at the base of the new stem, their 
function as protecting envelopes ceasing when growth is 
well started. 

46. Kinds of buds. — Sometimes the bad develop- ;. 

stem and clusters of nowers instead of leaves, this is espe- 
cially true of those buds which are borne near the lip of 
last year's growth. So buds may be of several kinds, con- 
sidered from the standpoint of the structure which they 
develop: leaf "buds, flower buds, or in many cases, mi 
buds, giving rise to both flower and leaf. 

Whatever structure develops from the bud. it is plain 
that it is simply an undeveloped branclilet, while a branch- 
let is a developed bud. This may be made somewhat 
clearer by a study of a soft, maple twig of two or three 
years' growth. At some of the nodes there may be found 
short branchlets ; they may supplant all the buds on the 
twig, or seem irregularly scattered, but in any case, close 
examination will show that where there occurs a branchlet 
there is no bud. but the branchlet occupies exactly the 
place in which a bud was to be expected. 

The bud scales, it has been stated, are protective organs. 
These are essential for the bud in order to protect if froni 
the extreme cold of winter and from the effect of sudden 
changes of temperature. In addition to these scales, bads 
often have a large amount of woolly and resinous sub- 
stances for greater protection. 

All of the buds above mentioned are winter hi 
capable of living through the colder months : I ~ear. 
In the herbs of temperate climates and even in trees and 
shrubs of tropical regions, the buds are often naked* that 



BRYOPHYTES-PTEKIDOPHYTES — BUDS 31 

is, nearly or quite destitute of scaly covering. This can 
be seen in the case of the bud of the common geranium. 

Sometimes at a node of certain plants, there may be 
found extra buds; these are called accessory buds. Buds 
often occur in irregular places ; that is, not terminal nor 
in or near the axils of the leaves. These are called adven- 
titious buds, and may spring from the roots as in the silver 
leafed poplar, or from the sides of the trunk as in our 
American elm. In many trees, as maples and willows, 
they are sure to appear when the trees have been cut back. 

All of the buds produced by a stem do not develop at 
the same time. Some may remain dormant, and this inac- 
tive condition may last for many seasons. Finally the bud 
may die, or some injury to the tree may destroy so many 
other buds as to leave the dormant ones an extra supply of 
food, and then they will develop. 

47. Vernation. — The arrangement of leaves in the 
bud is called vernation. This arrangement varies greatly 
in different plants. Sometimes they are fan plaited, some- 
times rolled, sometimes folded flat. The significance of 
this may be understood when we consider that two impor- 
tant purposes are to be served: (1) the leaves must be 
stowed away as closely as possible in the bud and (2) 
upon beginning to open they must be protected from too 
great heat and dryness until they have reached a certain 
stage of firmness. 

QUESTIONS 

1. What are some of the characteristics of Bryo- 
phytes I What plants are included in this group ? How 
do Bryophytes compare with Thallophytes ? 

2. How many kinds of reproduction are exhibited by 
this group \ What is alternation of generations ? 

3. What are liverworts ? Where found ? 

4. What is marchantia polymorph a ? Of what does 
the plant body consist ? What are gemmae ? Where found ? 
What is their use ? 



32 HOME STUDY-BOTANY 

5. Have you made a close study of the picture on 
page 20 ? 

6. Describe the organs concerned in sexual reproduc- 
tion. How is fertilization accomplished ? 

7. What is an oospore ? Into what does it develop ? 
What are elaters ? What is their use ? 

8. How is alternation of generations illustrated in 
the liverwort ? What is the advantage of alternation of 
generations ? 

9. What are mosses ? Describe the process of vegeta- 
tive reproduction. What is peat? 

10. What is the protonema ? Where do the moss plants 
originate? Where are the archegonia and antheridia pro- 
duced ? What is the process of 1 ertilization ? Describe 
the sporangium. 

11. Do you see clearly the rhizoids, the buds, and the 
leafy branches, of the older protonema in the picture on 
page 23 ? 

12. What classes of plants are included in the group 
of Pteridophytes ? What is the most important character- 
istic of Pteridophytes ? 

13. Where are the spores of the fern produced ? To 
what does a fern spore give rise on germination ? Where 
are the antheridia and archegonia of the fern ? To what 
does the oospore give rise ? 

14. Does the picture on page 25 showing the antheridia 
and the archegonia help you to understand how the oospore 
is formed ? 

15. What is the leafy portion of the fern called ? What 
is a sorus ? Of what is it composed ? 

16. Have you studied carefully the picture on page 
27? 

17. State two facts characteristic of the ferns. 

18. Why are Spermatophytes often studied alone as 
botany ? Why are they called seed plants ? Of which gen- 
eration is the plant body of a Spermatophyte ? 

19. To what points is the great dissimilarity of twigs 
due ? What is a leaf scar ? What is the node of a stem ? 
The internode ? Are the internodes all of the same length ? 



BRYOPHYTES-PTERIDOPHYTES-BUDS 33 

20. What is a terminal bud? An axillary bud? Why 
is each so called ? What is the alternate arrangement of 
buds \ The opposite arrangement ? The whorled arrange- 
ment \ 

21. What is the structure of a bud ? What are the 
kinds of buds ? What is a bud ? What is a branch ? 

22. Of what use are the bud scales? What else do 
buds have for this same purpose ? What are naked buds ? 

23. What are accessory buds? Dormant buds? 

24. What is vernation ? What is its significance ? 

25. Where is the stem of the fern? Does it live more 
than one year ? Under what conditions do ferns grow best ? 

26. Have ferns been more successful in former times 
than at present ? 



LESSON III 

STEMS 

4S Use of the stem. — To prepare its food, a plant 
niust have certain raw materials which it takes into its 
svsteni by means of roots and leaves. These raw materials 
are taken from the air. the earth, and the water. The 
stem is that organ of the plant which serves to bring the 
roots and leaves into communication with each other. 
Throngh its tissues the various food materials and fluids 
are distributed to the growing and working parts. The 
stem also serves an important purpose in holding up the 
buds, flowers, leaves, and fruit to the light and air. 

■A9. Classes of stems. — According to structure, stems 
may be all grouped in two classes. One class may be rep- 
resented by the shoots of the elder. This has a large 
amount of woodv tissue, having a definite arrangement. 
The other class may be represented by the corn stalk, and 
in this there is a smaller amount of woodv tissue, which 
is scattered irregularly through the stem. 

Plants belonging to the elder type are called dicotyle- 
dons. Those belonging to the corn stalk type are called 
monocotyledons. The significance of these name? will 
appear later. 

50. Monocotyledons.— In a cross section of the stem 
of the corn, made between the nodes, there will be seen to 
be two kinds of material: (1) the predominant portion, 
or piihj and (2) the wood, represented by numerous fibers 
scattered through the pith, more numerous toward the 
outside. 



STEMS 



35 




pppii 



Fig. 214. Section of stem of 
corn, showing the scattered 
bundles, indicated by black 
dots in cross-section, and by 
lines in longitudinal section. 
—From "Plant Relations.'" 

From Coulter's Plant 
Structures. Copyright, 1899, 
by D. Appleton & Co. 



The cells of the pith are so large 
that they may be distinguished 
with the aid of a hand lens. They 
are very thin-walled and all very 
much alike. They build up a very 
light vegetable tissue. Such a tis- 
sue is called parenchyma. It is 
the tissue of piths and the soft 
parts of plants generally. 

51. Fibro -vascular bundles. — 
Dissecting out one of the fibers it 
will be seen to be of great length 
and also to possess considerable 
strength. If the end has been cut 
smoothly, the lens will disclose 
about four large openings. These 
are the ends of the tubes or vessels 
as they are called, whence the fiber is called vascular. The 
fibers make up the fibro-vascular system of the plant, and 
each is called a fibro-vascular bundle. 

These fibro-vascular bundles in all stems form a con- 
ducting medium through which the water and dissolved 
foods move. In the case of the woody stems they are 
lacked so closely that their vascular nature is not made 
visible except through microscopic study of the tissue. 

52. Mechanical function of bundle arrangement. — 
The arrangement of the bundles in monocotyledonous 
stems has an important mechanical function. Looking at 
the cross section of a cornstalk, the bundles near the out- 
side will be seen to be smaller, but are more and more 
packed together. In other monocotyledonous stems, as in 
the grasses, the bundles are arranged in the form of a 
hollow cylinder. 

This gives very light, but at the same time, strong stems. 
It is well known that an iron or steel tube of moderate 
thickness has much more strength than a solid rod of the 
same weight per foot. The cornstalk is a solid cylinder, 
but is filled with very light pith. 



HOME STUDY— BOTANY 

These steins also have a flinty, outer layer of the stock. 
which adds to the stiffness of the stem. 

53. Dicotyledons. — Take a shoot of the elder, and cnt 
it squarely and smoothly off. preferably in the thinner 
portion. Dampen the cut surface a little to bring ont the 
structure. It may be seen that the stem consists of three 
parts: (1) the outer called the bark or cortex. (2) the 
woody portion, and (3) the central portion or pith, some- 
times called the medulla. Each of these portions is cir- 
cular in outline, and in all woody stems each occupies 
always the same relation as regards position. 

51. The bark. — TTith care the bark of the elder twig 
may be found to consist of three layers, the outer or corky 
layer, the middle or green baric, and the inner or fibrous 
layer. This primitive arrangement persists usually bat a 
short time, in some cases, however, much longer than in 
others. If the layers are to endure they must be renewed 
from within, and the inner growth usually results in the 
pushing off of the outer layers. In most trees the inner 
bark finally contains masses of thick walled cells, much 
hardened, and is the only part of the bark that contains 
any living cells. The outer bark layers split up and dis- 
appear, or sometimes uiay cling for years, as in the case of 
the cork oak, the outer bark of this tree forming the cork 
of commerce. 

The way in which this old bark falls off from different 
trees furnishes an interesting topic for study. Sometimes 
it falls in flakes of various sizes and shapes, as in the case 
of many of our common trees. In the birch it peels off 
in bands or sheets around the stem, in the grapevine it 
peels in long strings, and in the case of the apple, it strips 
around the stern. 

The roughening and cracking of the inner bark which 
remains on the stem is due in large measure to the effect 
of the weather. 

In the outer bark of young twigs, and on the bark of 
rather old stems, in the case of some trees, are to be found 
openings called lenticels. These first appear as roundish 



STEMS 



37 



spots of small size, but as the twig on which they appear 
increase's in diameter, the lenticel spreads at right angles 
and sometimes forms rather large transverse scars or slits, 
as in the cherry. The purpose of the openings is to admit 
air to the interior of the stem. 

55. The wood. — The first thing of importance in 
regard to the wood is to remember that it is composed of 
fibre-vascular bundles, just as in the case of the cornstalk, 

but that here we have 
the other type of ar- 
rangement of the bun- 
dies, and that is, in the 
form of a ring which 
takes up by far the 
greater portion of the 
older stems. In many 
of the older stems the 
pith has nearly disap- 
peared, but in shoots 
of a single year's 



growth, the wood, pith, 
and bark form rings 
all of about the same 
thickness. So with age 




Fig. 217. Section across a twig of box elder 
three years old, showing three annual rings, 
or growth rings, in the vascular cylinder; the 
radiating lines (m) which cross the vascular 
region (w) represent the pith rays, the princi- 
pal ones extending from the pith to the cor- 
tex (c).— From " Plant Relations." 

From Coulter's Plant Structures. Copy 
right, 1899, by D. Appleton & Co. 



the woody portion in- 
creases, and the others 
decrease in proportion- 
ate amount. 

In both older and vounojer woodv stems, the bundles are 
separated at quite uniform intervals by lines radiating 
from the central pith. These lines are parts of the pith 
which extend between the bundles, and are called medul- 
lary rays, parts of the medulla. 

As the fibro-vascular bundles increase, these rays must 
of necessity become smaller on account of the lessening 
space, and so in stems of medium age are represented only 
by thin plates. The cells of these rays are of use in hold- 
ing the food which the plant in temperate and cold cli- 



38 HOME STUDY — BOTANY 

mates stores up in summer and fall for use the following 
spring. In the very young plant these rays also serve as 
channels for the transference of fluids from stem to bark 
and the reverse. 

These cells, it is said, are among the longest lived of all 
plant cells, often retaining their vitality for more than a 
century. This is perhaps due to their importance. 

56. The cambium. — In thin cross sections of young 
woody stems, there may he seen by the aid of the micro- 
scope, a layer of very delicate cells, like those of the pith, 
but much smaller, and even more thin-walled. This layer 
is between the wood and the bark. It is called the cam- 
bium layer, and is the growing portion of the stem, that 
is, it is the only portion that has power to develop new 
cells and thus cause it to grow:. 

In the growing season, these cambium cells do three 
things: (1) they increase their own number, (2) some 
of them on the outside produce new bark cells, thus form- 
ing a new layer on the inside of the bark, (3) some next 
the wood become changed into wood cells, and so add a 
new layer to the wood. 

The presence of the cambium in the stem is illustrated 
in the early spring, when this layer is apparently most 
active, and it is so gorged with rich, nutritive material, 
that the bark seems to be loose from the wood. The sweet 
taste of this pulpy layer as found in the slippery ehn and 
other stems, is a familiar evidence of the nourishment con- 
tained in it. 

57. Increase in diameter. — The amount added to the 
stem in a year by the aid of this cambium layer can be 
determined to some extent. In temperate climates, where 
there is an annual growing and resting period for plants, 
the cells formed by the cambium in the spring are larger 
and more distinct ; those formed in the fall are less so, and 
so there is usually a distinct line caused by the difference 
in the character of the cells at the different times. The 
concentric rings thus formed will give us by counting 
them, an idea of the a<2;e of the tree. It will not s;ive the 



STEMS 39 

exact age, for sometimes there is more than one growth 
period in a. year. Over twelve hundred layers have been 
counted in the stumps of some of the giant redwoods of 
California, and there are trees now living that are prob- 
ably much older. 

58. Knots. — Sometimes the annual rings in trees, are 
interrupted by knots. These are formed by fibro-vascular 
bundles which have been connected with buds on the stem. 
As the bud stows the fibro-vascular bundles increase in 
number and form a cylinder of wood, at an angle with the 
annual rings. If the branch dies before the growth of the 
stem stops, the knot will be buried under the new layer 
of wood. Lumber free from knots is obtained from trees 
which have grown in a dense forest, where the lower 
branches through inability to obtain light have died long 
before the tree was felled. 

59. Growth of stems. — It has been seen in the study 
of the dicotyledonous stem, that growth takes place through 
the agency of the cambium layer, and consists of succes- 
sive additions to the outer part of the stem. Hence the 
stem increases in diameter and is also increasing in length. 

For the most part, monocotyledonous stems do not in- 
crease in diameter, but onlv in length. There is no cam- 
bium layer in the stem, by which such growth might be 
accomplished. Where such stems do increase in size it is 
only through the increase of the individual tissue elements, 
but they do not increase the number of the bundles. 

The old terms for the two classes of stems, exogens (out- 
side growers) and endogens (inside growers), are no longer 
generally used. They were so called because of the mis- 
taken belief that the monocotyledonous stem increased in 
diameter by the growth or addition of new bundles inside 
the stem. 

The terms monocotyledons and dicotyledons arise from 
the number of primary seed leaves found in the seeds of 
the two different types of plants. The seed leaves are 
called cotyledons. The seeds of all plants having the wood 
arranged in circles around the pith, have two cotyledons, 



40 HOME STUDY — BOTANY 

hence these plants are rf /cotyledons. The only exception 
to this is the conifers (trees of the evergreen types), which 
have more than two cotyledons in the seed. Those plants 
having the bundles irregularly scattered in the stem have 
but one cotyledon in the seed, hence are monocotyledons. 

60. Work of the stem. — The function of the stem 
as a conductor of material to and from parts of the plant 
has been suggested. This material which it conducts is 
commonly called sap and consists of water with various 
substances dissolved in it. This sap is not the same sub- 
stance in all parts of the plant, but differs according to the 
part of the plant in which it is found. Sometimes it is 
nearly pure water, and at other times it contains great 
stores of food. 

61. Upward path of sap. — If some branches newly cut 
from an apple tree are allowed to stand for several hours 
with the lower end in red ink, and then are examined in 
successive portions of the stem, it will be seen that the ink 
has ascended through the newer lavers of the wood. As 
forest trees will live after the heartwood has decayed, and 
some will live after the bark has been removed in a ring 
extending around the trunk, it may be concluded that sap 
containing food materials in a crude form ascends through 
the newer wood to the leaves. In the leaves it is made into 
the elaborated forms. 

62. Downward path of sap. — If a willow shoot is 
girdled by removing a strip of the bark and then placed in 
water, after a few weeks that portion of the twig above the 
girdle will send out roots abundantly, while but few, if 
any, will be sent out from the portion below the girdle. In 
all the region above the girdled ring there is evidently an 
extra amount of food, while the lower contains but little. 
This would tend to prove that the bark conducts elaborated 
sap downward through the stem, for the girdled portion 
here prevents the food from passing into the lower part of 
the stem. 

63. Movement of water in the stem. — How the 
movement of water in the stem is accomplished is not clef- 



STEMS 4:1 

initely known, though many theories are advanced to 
explain the phenomenon. It is not, as has so often been 
stated, a. circulation similar to the circulation in animals, 
for the tubes through which the movement takes place are 
not continuous and open like those of animal bodies, but 
are sets of closed vessels communicating with each other 
in various ways. 

If a section is made of a stem with its attached leaf, the 
bundle will be seen to run out into the leaf, and so it is 
evident that there is a continuous route for the passage of 
water from the root to the leaves. 

64. Duration of stems. — A rapid survey of a large 
number of the stems of common plants in regard to their 
duration, will serve to classify them. They may be placed 
in two classes: (1) those which die completely on the 
approach of winter, as the tomato, or die down to the 
ground, as the asparagus, and (2) others that persist, 
retaining their stems from year to year. Stems which die 
before frost are called herbaceous ; persistent stems, by 
way of contrast solely, are called woody. All the woody- 
stemmed plants of northern latitudes, except one or two, 
are dicotyledons. It is only in the tropical regions that 
monocotyledons exhibit persistent stems. 

In the case of the persistent dicotyledonous stem, it is 
only the outer portion of the stem which lives. The inner 
part of the stem, called the heartwood, and often dis- 
tinguishable from the rest of the stem by a difference in 
color, is no longer living. This is demonstrated by the fact 
that the water current has abandoned it, and also by the 
fact that hollow trees live and flourish as well as those that 
are solid. 

The outer part of the stem called the sapwood is the 
part which, in general, contains living tissue, and through 
which, the water current still passes. 

65. Habits of stems. — As regards their habit of 
growth, stems may be divided into several classes. They 
may be erect, as in the case of most of our familiar plants, 
or they be climbing, prostrate, or repent. 



42 HOME STUDY — BOTANY 

Climbing plants have various devices by which, they 
make their way up to light and air. In the morning glory 
the ascent is made hy twining the stem around a support. 
The grape climbs by means of tendrils, organs developed 
for the purpose of holding the plant fast to a support. The 
Virginia creeper illustrates two methods of climbing. One 
is by means of little rootlets which stow into the wall or 
tree trunk which forms the support, the other is by means 
of a specially adapted tendril. These have little discs or 
suckers at their tip, by means of which the plant may 
obtain a firm footing on a comparatively smooth wall. 

Prostrate stems are illustrated by the pumpkin and 
melon vines, whose whole length lies on the ground even 
though the tip does show a tendency to rise. 

Repent stems are the creeping stems. They also are 
prostrate but attach themselves at intervals to the soil by 
bunches of roots. The clover and strawberry are good 
examples of this type. 

66. Special forms of stems. — The function of the 
stem in general has been suggested, but there are some spe- 
cial forms of stems to be considered which have a different 
and additional function. In those plants which die down 
to the ground on the approach of winter, there must be a 
storage of food either in the roots or in some portion of 
the stem which is underground. 

So some plants have developed certain subterranean 
stems which are known as bulbs, tubers and rootstocks. 
The onion and the lily furnish examples of bulbs, while 
the underground portions of Solomon's seal, the raspberry, 
and ferns, give us examples of rootstocks. The most com- 
mon of all tubers is the potato. 

67. The potato a stem. — A study of the potato will 
develop the fact that it is a greatly modified stem. If a 
potato is cut into portions each containing an eye, and 
these portions are then planted, new plants will develop 
from each piece. This is because the eyes are really buds, 
or undeveloped branches. The arrangement of the buds 



STEMS 43 

can easily be made out. A little scale is placed at the 
lower edge of each eye, and this is a rudimentary leaf. 

Splitting a potato lengthwise the three parts of the stem 
may be distinguished: (1) the pith very large, (2) the 
wood, a faint brown line around each section, and (3) 
the bark rather thick. Outside of this is a thin skin, the 
epidermis. 

Chemical tests will prove that the mass of this potato is 
made up very largely of starch, which is a form of food 
well adapted for storage purposes. That this is a store of 
food for the plant's use is shown by the fact that when the 
potato has been sprouting for some time, it is known that 
there has been a loss of material from the tuber. 

68. Uses of tubers and bulbs. — In countries having 
a wet and a dry season, tubers and bulbs carry the plants 
through the dry season. When the rainy season returns, 
the plants develop and bloom very rapidly, causing a mar- 
velous transformation in the landscapes of such countries, 
in a very short time. 

QUESTIONS 

1. What is a stem ? What functions does it have ? 

2. How many classes of stem structure ? What are 
dicotyledons ? Monocotyledons ? What are the type plants 
of these groups ? 

3. What are the parts of the stem of the corn ? How 
arranged ? What is a fibro-vascular bundle ? What part 
of all stems is formed by these bundles ? 

4. Have you examined with a lens a cross section of 
a corn stalk? Does the picture on page 35 fairly repre- 
sent what you observed ? 

5. What is the mechanical function of the lrrauge- 
ment of the bundles in the stem of the corn ? 

6. What are the parts of a stem of the elder ? What 
is the shape of each part? What is the relation of the 
parts ? 

7. Of how many layers does the bark consist ? What 
part of the bark is living ? What becomes of the old bark ? 
What is cork ? 



41 HOME STUDY — BOTANY 

8. How does the old bark fall from different plants \ 
To what is the roughening of the bark due ? What are 
lenticels \ What is their purpose ( 

9. Of what is the wood composed '. What is the rela- 
tive size of pith, wood, and bark, in old and young stems ? 
What are medullary rays \ What is their importance ? 

10. By inspecting a cross section of a large twig, have 
you verified the facts shown in the picture on page 37 ' 

11. Where is the cambium layer i What is it ' What 
can it do i How is the formation of annual rings in the 
wood of trees explained ? How are knots formed i 

12. Compare the growth of the dicotyledonous and 
monocotyledonous stem. 

13. From what do the terms dicotvledons and mono- 
cotyledons arise \ 

14. What is the function of the stem \ What is sap ? 
Is sap always the same ? Why not i 

15. Through what part of the stem does the sap 
ascend ? How is this proven I In what form is it when 
ascending \ When descending ? 

16. What part of the stem conducts the elaborated 
sap ? How is this proven ? How does the circulation 
of sap through the stem compare with animal circulation ? 

17. What is an herbaceous stem? A woody stem? 
How much of a woody stem is living tissue '( What is 
heartwood ? Sapwood ? 

18. How are stems classed according to habits of 
growth \ How do climbing plants make their way up to 
light and air ? What are prostrate stems ? Repent stems ? 
Erect stems ? 

19. What additional function may some stems have ? 
What is a subterranean stem ( What is a bulb i A 
tuber \ A rootstock ? 

20. Why is the potato to be classed with stems ? How 
is it evident that the potato is a form of stem for food 
storage ? Of what use are these subterranean stems to 
plants ? 



LESSON IV 

ROOTS AND LEAVES 

69. Variation in roots. — Koots in their development 
do not show as much variation as the other organs of the 
plant. This is dne to the uniformity of conditions to 
which they are exposed in the ground. Aerial roots, 
belonging to plants which live wholly in the air, usually 
show more of a tendency to modification than do the soil 
roots. Whatever the type of the root may be, it is serving 
the function of either an absorbent organ or a holdfast and 
often performs both functions. 

We know that the general direction of roots is down- 
ward, but what efforts the plant will make to keep this 
direction is not always known. If seeds of various plants 
are put in the ground and wrong side up the root will turn 
as it grows and take its appropriate direction. For this 
reason the root is sometimes called the descending axis and 
the stem the ascending axis of the plant. 

70. Kinds of roots. — The first root that starts out 
from the seed is called the primary root. Other roots of 
the plant which succeed it in development are called second- 
ary roots. In some plants the primary root continues to 
develop until it has become larger and stronger than the 
rest of the roots. This is called the tap root. The dande- 
lion possesses a well developed tap root, as do many other 
weeds and also many trees. 

In some cases the primary root instead of soon sending 
out secondary roots, grows thick and fleshy, as in the beet 
and the carrot, and this fleshy root has an additional func- 
tion, the storage of food for the purposes of carrying the 



46 



HOME STUDY — BOTANY 



e p p! p e 



plant over a period of enforced rest. Those roots which 
do not deYelop the fleshy f omi but retain the thread-like 
forms which they first deYelop. are called fibrous roofs. 
Roots are different from stems in that they do not bear 
buds or leaves. It is true that a few fleshy roots do bear 
buds, but in this case they are adventitious. The sweet 
potato is a root, but it bears this type of buds, and these 
give rise to the new plants. 

71. Structure of roots. — Though composed of essen- 
tially the same elements that are to be found in the stem, 

the relation of these parts to 
one another in the root 
changes in some respects, 
and there are some addi- 
tional structure-. 

By the aid of the micro- 
scope, the structure of a 
young root of any common 
plant may be shown. Upon 
the tip of the root will be 
seen a cone-like structure : 
cells. This is for the pro- 
tection of the tip of the : t . 
as it pushes its way through 
the soil, and is called the 
root cap. 

The woody portion of a 
root is in the form of a 
cylinder, forming a tough 
and fibrous central axis, and 
around this is a wide regi 
of spongy structure, which is the cortical portion. 

These young roots are also provided with root hairs. 
These are delicate tube-like structures which are outgrowths 
from the epidermis of the root, and are found most abun- 
dantly a short distance above the tip of the root, which is 
the growing portion. These root hairs are the absorbing 
organs of the plant. They are so small that they are able 




Fig. 275. A longitudinal section through 
the root - tip of shepherd's purse, 
showing the plerome (pi), surround- 
ed by the periblem (p), outside of 
perihlem the epidermis (e) which 
disappears in the older parts of the 
root, and the prominent root-cap (c). 
— From " Plant Relations. 

From Coulters Plant Structures 
Copyright, 1899, by D. Appleton & Co. 



ROOTS AND LEAVES 47 

to penetrate the crevices of the soil and take up from it 
all the moisture and dissolved food needed by the plant. 
Their great number upon the many divisions of the root 
gives to the plant a very large amount of absorbing surface. 

These hairs are so small as to be invisible in many 
ea>es, but on some plants are so large that they show 
plainly. This is true of the clover and the corn. These 
plants, however, if pulled from the earth will not show the 
root hairs, for they are broken off in the process. But. if 
the seeds of these plants are developed at the surface of a 
glass of water, the root hairs can readily be seen. 

The delicacy of the root hairs will explain why plants 
often do not grow when transplanted. It is plain that root 
hairs are very necessary structures, and in the unavoidable 
handling they are broken off. The plant having nothing 
by which to obtain food and moisture in its new situation, 
is unable to develop new root hairs and so dies. Trees that 
are transplanted in the winter time are usually the most 
successful in their new situations, because the frozen 
ground forms a ball around the roots and prevents the 
destruction of the root hairs. 

The root hair is not a young root. It has a very short 
duration of life. But as rapidly as the hairs die, new ones 
are found to take their places on the portion of the root 
where they are most needed. 

72. Absorption of water. — In order to understand 
how it is possible for plants to receive water from the soil, 
a physical process known as osmosis must be understood. 

A theory in physics states that the molecules of fluids 
are in constant, imperceptible movement. This movement 
may be made perceptible if we take a salt solution and put 
it in a jar which can have the opening closed bv a mem- 
brane, as a sheet of parchment, and place it in a jar of 
water. Here we will have the salt solution on one side of 
the membrane and pure water on the other. After a time 
the salt solution will be seen to have absorbed some of the 
water through the membrane, and increased its own 
volume. 



48 HOME STUDY — BOTANY 

Soil water passes through the walls of the root hairs and 
mingles with the liquid contents of the cell by this same 
process. This soil water, which is practically identical 
with spring water, is separated from the more or less 
sugary or mucilaginous sap inside of the root hairs, only 
by their delicate cell walls, which are lined with a layer 
of protoplasm. The soil water will pass very rapidly into 
the plant through these walls, but very little if any sap 
will come out, and this water will be carried from cell to 
cell throughout the plant by this same osmotic action. 

73. Selective power of protoplasm. — The activity of 
protoplasm is very well illustrated by this absorptive 
power which it exhibits in the cells of the root hairs. 
Plants of different species growing in the same soil usually 
take from it varying amounts of mineral matters. Some 
will take more lime than others, and some more silica and 
so on. This difference is due undoubtedly to the selective 
action (see page 4) of the protoplasm in the absorbing 
cells of the roots. It acts here as though endowed by intel- 
ligence, not simply permitting the food materials to pass 
through, but letting in some and letting out others, keeping 
in some and keeping out others. 

74. Soil water. — The water which is valuable to the 
plant is not free water, but is in the form of a thin film 
of moisture around each tiny particle of the soil, and 
adheres to the particle. So the finer the soil is the greater 
the number of particles, and the consequent larger amount 
of film moisture which is placed ready for the plant's 
absorption. So the fineness of the soil is an essential thing 
in the growth of plants, not only that the root hairs may 
more easily penetrate it, but also that the amount of water 
which the plant can use may be increased. Root absorp- 
tion may be carried on thus in a soil that to us seems to be 
mere dust. 

75. Extent of root systems. — It is difficult to deter- 
mine the total length of the roots of ordinary plants, 
because of the fact that when we take a plant up from the 
earth a large part of the roots must be broken off and left 



ROOTS AND LEAVES 49 

behind. But some studies of plants have been made in 
regard to this point, and it has been found that the length 
of the roots is much greater than is ordinarily supposed. 
The roots of winter wheat have been found to extend to a 
depth of seven feet. 

In soils where the water supply is poor, the root systems 
will often be enormously developed, as they will extend in 
all directions and go long distances for water. It is said 
that the Mexican farmers follow the roots of the mesquite 
bush as guides when digging wells, and they have been 
found to extend to a depth of seventy feet and more. 

76. Duration of roots. — According to the length of 
time the root will live, plants are classed as annuals, bien- 
nials, and perennials. An annual is a plant in which death 
of the whole plant system occurs at the end of the season. 
A biennial plant endures for two seasons, and when a plant 
endures for three or more seasons it is said to be perennial. 

In the last two classes it is evident that there must be 
a storage of food to carry the plant over the winter periods. 
How it is done with the biennials is illustrated in the case 
of the fleshy roots, and the roots of perennials, though not 
fleshy roots, also contain a large amount of stored plant 
foods. In the case of some perennials, as the rhubarb, the 
plants die down to the ground in the fall, and make a 
rapid growth in the spring from the materials stored up 
in the roots. 

LEAVES 

The higher plants have the leaves developed as special 
organs to do certain parts of the work of nutrition. This 
work is carried on by the green parts of other plants which 
do not bear leaves, but the leaf as a separate organ can do 
it better. 

77. Duration of leaves. — A study of a maple twig 
and one from the pine, taken during the winter, will show 
that leaves are of two kinds, those which fall on the 
approach of frost and are termed deciduous, and those 



50 HOME STUDY — BOTANY 

which remain on the stem from season to season and are 
termed 'persistent. 

The leaves of the evergreen are persistent only for a 
number of years, two or three, or they may last for ten 
or twelve years. That they do not persist for longer periods 
of time may be shoAvn by the fact that all the branches 
of older growth are not covered with them, but that from 
the older portions of the leaves have fallen, leaving the 
branches roughened by numerous leaf scars. 

In the tropics many trees retain most of their leaves the 
year round, dropping a leaf occasionally, but no great 
number of them at any one time. So there, most trees are 
evergreens, just as the pines and their allies are evergreen 
in our northern latitudes. 

78. Fall of the leaf.— The leaf during the latter 
part of the season is preparing for its separation from the 
stem. A layer of cells is formed between the stem and 
the leaf by the division of all the living cells in the plane 
of separation. At a later stage, a layer of cells in the 
middle of this layer is absorbed, and the leaf becomes 
divided from the stem. The wound on the stem either 
simply dries up, as in the case of the fern, or is closed by 
a layer of cork, forming a leaf scar. 

So it is seen that the fall of the leaf is not due to the 
action of frost, but is only hastened by it. The leaf dies 
and would fall at a later stage if the frost did not inter- 
vene to bring about its earlier separation from the stem. 

79. Arrangement of leaves. — A study of some twigs 
of the oak and maple will show that leaves have the same 
arrangement as buds. On the oak there is but one leaf 
at a node, so the arrangement is alternate. On the maple 
the leaves are placed two at a node on opposite sides of 
the stem and are opposite. On the catalpa three leaves are 
found at a node, forming a circle and hence are said to 
be wliorled. 

80. Parts of a leaf. — The leaf of the common gera- 
nium furnishes good material for study. It will be seen 
to consist of three parts: (1) the long slender stalk or 



ROOTS AND LEAVES 51 

petiole, (2) the thin expanded portion of the leaf, the 
blade, and (3) at the base of the petiole are attached a 
pair of green, leaf-like appendages, the stipules. A leaf 
exhibiting all these parts is said to be a model or typical 
leaf. 

Leaves may consist only of blades and petiole, lacking 
stipules, or they may also lack the petiole, thus consisting 
only of the blade. In the latter case they are said to be 
sessile. The stipules are not always leaf -like, but may 
be spines or prickles as in the locust, or tendrils as in the 
smilax or greenbrier. The structure and functions of 
leaves, together with the kinds of leaves, will be discussed 
in the next lesson. 

QUESTIONS 

1. Why do not roots vary as much as the other organs 
of the plant ? 

2. What are aerial roots ? Why do they tend to vary 
more than soil roots % 

3. What are the two main functions of roots ? 

4. Why is the root called the descending axis of the 
plant ? What is a primary root ? A secondary root ? 

5. What is a tap root ? What is a fleshy root ? A 
fibrous root ? 

6. Do roots bear buds ? What is a root cap ? Its 
purpose ? 

7. After studying the illustration on page 46, do you 
understand the construction and use of a root cap ? 

8. Where is the woody portion of the root ? Has a 
root bark ? 

9. What are root hairs ? Where found ? Of what 
value are they to the plant ? Why are they so numerous ? 

10. Why do plants often not grow when transplanted ? 
Why is it better to transplant trees in the winter time ? 

11. What is osmosis ? How does water pass into the 
cells of the root hairs ? How do these root hairs illus- 
trate the activity of protoplasm ? 



52 HOME STUDY — BOTANY 

12. In what form is the soil water which is valuable 
to the plant ? Why is it well to keep the earth about a 
plant in a finely divided condition ( 

13. "What can be said of the extent of root systems? 
In what regions are the root systems often best devel- 
oped ? Why \ 

14. What are annuals ? Biennials ? Perennials ? 
When and how does the root act as a storage organ ? 

15. What is the general function of leaves? Is this 
work carried on by the leaves solely ? 

16. What are deciduous leaves? Persistent leaves? 
For how long a period do persistent leaves remain on the 
stem ? 

17. How does a leaf fall in the autumn ? Is the frost 
responsible for its fall ? 

18. What are alternate leaves \ Opposite leaves ? 
Whorled leaves ? 

19. What are the parts of a leaf? What is a typical 
leaf ? What is a sessile leaf ? Are stipules alwavs leaf- 
like ? 



LESSON V 



LEAVES, CONTINUED 



81. Structure of leaves. — The leaf of the white lily 
offers good material for the study of the structure of a 
typical green leaf. With a knife blade there may be 
stripped from the outer surface a thin layer. This is a 
transparent membrane, the epidermis. If this epidermis 
is now placed under the microscope, its cellular structure 
can be seen very distinctly. At intervals where two cells 
meet may be seen an opening which is guarded by two 
thin-walled cells. These are the breathing pores or 
stomata (singular stoma) by means of which direct com- 
munication is established between the external air and 
that inside the leaf. 

The cells around the opening, or 
guardian cells of the stomata as they are 
called, are soft and delicate, and have 
the power of regulating the size of the 
opening between them. They may 
straighten out so that the slit is closed, 
or become more convex so that the slit 
is more widely opened. These openings 
are small but very numerous. The total 
number upon an average leaf is very 
large. A space equal to the area of an 
ordinary pinhead may have as many as 
2,000 stomata in it. 

The advantage of the small size of 
the stomata is that they are not readily 
clogged by water upon the surface of the 
leaf. Many leaves also have wax or 
bloom upon their upper surfaces to aid 
the water in rolling off and thus keep the 




Fig. 29. A single 
stoma from the 
epidermis of a 
lily leaf, show- 
in g the two 
guard-cells full 
of chlorophyll, 
and the small 
elit-like opening 
between. 

From Coulter's 
Plant Relations. 
Copyright, 1899, by 
D. Appleton & Co. 



54 



HOME STUDY — BOTANY 



stoniata clear. If the stoniata were to become filled with 
water their activities would cease until they were fre I 
from it. 

Hairs of various sorts are also present on the leaf sur- 
face to keep dust from clogging up the stoniata. Many 
leaYes haYe stoniata on the under surface solely. This is 
especially time of leaYes haYing a horizontal position. With 
vertical leaves there is an equal distribution of stoniata 
on both surfaces. 

If a cross section of a leaf be examined under the micro- 
scope the epidermal cells will show very plainly, as clear, 




Fig. 275. A section through the leaf of lily, showing npper epidermis (ae), lower epi- 
dermis tie i with its stomata (st ). mesophyll (dotted cells) composed of the palisade 
region (f») and the sponsy region <sp) with air spaces among the cells, and two 
vane r cut across. — From " Plant Relations." 

From Coulter's Plant Structures. Copyright, 1899, by D. Appleton & Co. 

colorless cells. Just beneath the upper layers will be 
found a layer of cells, closely connected with each other. 
These are the palisade cells and contain the greater part 
of the green coloring matter of the leaf, the chlorophyll. 
Underneath the palisade cells are other rather s] _ 
cells of different shape, and these are arranged in groups 
leaving large intercellular spaces. These spaces can be 
traced through the section and the fact that thev connect 



LEAVES, CONTINUED 55 

directly with the stomata on the under surface will be 
made very clear. 

82. Function of each part. — The function of the 
leaf will appear a little later, but the particular function 
of each part may be stated briefly here. The epidermis 
prevents excessive evaporation, strengthens the parts 
beneath and prevents injuries to them. The palisade 
cells hold the green matter in such a way that it can 
receive enough, but not too much, sunlight, and the cells 
of the spongy part share the work of the palisade cells and 
also evaporate much water. The stomata admit air to the 
interior of the leaf, to the intercellular spaces. They per- 
mit oxygen and carbonic acid gas to escape, and they also 
regulate the evaporation of the water. The health of the 
plant is due in a large measure to the stomata. One rea- 
son why plants in large cities often fail to thrive is because 
the stomata become choked with soot and dust. 

83. Venation. — One other fact is to be noted in regard 
to the structure of the leaf. The soft parts are held in 
an expanded form by a network of woody fibers. These 
are the flbro-vascular bundles which are continued into 
the leaf from the stem, and serve to conduct the food 
materials into the leaf and to keep it in the expanded 
form. These bundles we call the veins, and their arrange- 
ment in the leaf constitutes the venation. The largest 
veins, which are the branches of the petiole, are called 
ribs. The different kinds of venation may be illustrated 
by leaves from the elm, geranium, narcissus or amaryllis, 
and canna. 

The elm leaf will show a prominent central vein, with 
secondary veins running obliquely from it, like the barbs 
of a feather, hence the leaf is ^innately veined or feather- 
veined. Small veinlets form a network between the sec- 
ondary veins, hence the elm is netted-veined, and being 
pinnate, is said to be pinnately netted-veined. 

In the geranium the large veins diverge from the end 
of the petiole like the fingers from the palm of the hand, 



5$ 



HOME STUDY — BOTANY 



and the leaf is thus palmately veined. It also lias netted 
reining and is palmately netted-veined. 

The aniaryllis shows a very prominent central rib, with 
numerous smaller veins, which extend from the base of 
the leaf to the apex, and no smaller veinlets forming a 
network can be distinguished. These vein? then are 




Fig. 215. Two types of leaf venation: the figure to the left is from Solomon's seal, 
a Monocotyledon, and shows the principal veins parallel, the very minute cross 
veinlets being invisible to the naked eye; that to the right is from a willow, a 
Dicotyledon, and shows netted veins, the main central vein unidrib) sending out 
a series of parallel branches, which are connected with one another by a network 
of veinlets. — After Ettixgshausex. 



From Coulter's Plant Structures. Copyright 1899, by D. Appleton & Co. 

approximately parallel, and as they diverge from the base 
the leaf is palmately parallel-veined. 



LEAVES, CONTINUED 57 

The canna has also a prominent central vein, but the 
secondary veins here are pinnate. The network between 
the veins cannot be distinguished and so the leaf is 
pinnately parallel-veined. 

84. The work of the leaf. — The leaf and in fact all 
the green parts of the plant form the laboratory of the 
plant. Here the crude food materials are prepared for 
use. Some of these crude materials the leaf obtains by 
direct absorption from the air, and some are brought to 
it in solution in the water absorbed by the roots. 

The work of the leaf can be carried on only' in the light. 
Sunlight is the best light, but plants have been found to 
grow well under the influence of strong electric light, 
This is because chlorophyll is the necessary agent in the 
work and chlorophyll forms only under the influence of 
light. This is demonstrated in the case of those plants 
which have been shut away from the light for some time, 
and have their leaves blanched in consequence. 

Some statements about the food of plants have already 
been made, but it is well to state clearly the fact that 
green plants are able to live without help from other 
organisms because they have the power of using inorganic 
material as food. They have the power of organizing this 
inorganic material, that is, making it into organic matter. 

85. Materials required. — The materials required by 
the plant in carrying on this organization are carbon 
(C), hydrogen (H), oxygen (O) and nitrogen (N), 
and more or less of sulphur, potassium, calcium, phos- 
phorus and other elements. The plant obtains these 
elements in the form of inorganic compounds. Car- 
bon it obtains from the carbon dioxide (C0 2 ) of the air 
and oxygen and hydrogen from the water (H 2 0) which 
it absorbs from the soil. The water holds in solution the 
various salts of nitrogen and other elements which are 
obtained from the soil. These substances can be used by 
the plant only when in the form of a gas or liquid, as they 
must pass through the cell wall. 



58 



HOME STUDY — BOTANY 



86. Photosyntax. — After a plant has obtained these 
inorganic compounds, it has the power to break them up 
into their elements, C, O and H, and to unite these again 
into compounds called carbohydrates (starch, sugar, etc.). 
At the same time some oxygen is formed as a waste 
product, and is giYen off to the air. This part of the 
plant's work is termed photosynthesis or photosyntax. 
words which indicate that the presence of light is neces- 
sary. The mechanism for the work is the chlorophyll 
bodies, which when exposed to the light are able to do this 
work. 

It is eYident then that green plants must haYe a good leaf 
exposure, both for light and air. and that they cannot live 
if kept in darkness. And it is not only the leaves that 
carry on this work, but all the green parts of the plant 
are engaged in it. 

v 7. Digestion and assimilation. — Alter the carbohy- 
drates are formed they serve as a basis for the further 
work of the plant. Adding to the carbohydrates other 
elements, particularly nitrogen and sulphur, the juant 



Cor 6 o/?y <fn?fr 



Pnottict 




rrotopfq s m 



COHNSy- <COHNS 




Hhoto Syntax 



• - 1 

rJ/tro<?fN% So/phur sa/fs O 



r\ SS i art fat/ on 



COiL 

{ 

X 



Rt$fH/r??n 



forms a class of very complex foods called proteids. These 
may be made in any part of the plant, they are not 
dependent upon light for their formation. 



LEAVES, CONTINUED 59 

These two substances thus made must be transported to 
the regions where they are needed, and therefore must first 
be digested, or made into soluble form. If the substance 
is insoluble, as the starch made by the plant, it is turned 
into some soluble form, as sugar, and is then transported. 

When the carbohydrates and proteicls are finally trans- 
ported to the places where they are to be used, they are 
then assimilated ; that is, they are made into whatever the 
plant requires, either the enormously complex substance 
protoplasm, which is itself a proteid and which then builds 
the plant structure, or they are transported to storage 
portions and there reconverted into insoluble forms, as 
starch and the like. 

8S. Respiration. — In order to do all this work the 
plant must have energy and this is obtained in the same 
manner as the animal body obtains it, through respiration. 
(See page 3.) The plant absorbs oxygen from the air, 
combines it with its protoplasm, and thus the protoplasm 
is oxidized. This oxidation is similar to that process by 
which a piece of wood burns, the union of oxygen with 
the wood oxidizes it, and releases energy which may be 
applied to an engine to> enable it to do work. 

In the plant cell the, union of oxygen with the proto- 
plasm releases energy by means of which the plant is able 
to carry on its work. The protoplasm in undergoing this 
oxidation is torn down, that is, it is broken up into several 
chemical compounds, some of which are used again by the 
plant, while others as water and carbon dioxide are given 
off as waste products. 

This absorption of oxygen and giving out of carbon 
dioxide goes on in all the organs day and night. When 
it ceases the death of the plant follows rapidly. If the 
plant cannot get oxygen from the air it may live for a 
short time upon that which is stored in the intercellular 
spaces, but this will suffice only for a few hours. 

This process of respiration it will be noted is exactly 
the reverse of photosyntax. It does not depend upon the 
chlorophyll bodies, for it goes on in plants and parts of 



•?; 



h : Mj 



- 1 : i .-. : ■ r 



plants which are not green. Il goes on in every living 

~ :z~ :: :Le ■ lin- 

Once it was thought that plants differ from animals in 
— e :; :: -_:■- ;:: ~:Z~~ : -::: ::: •_ lzixzzt : '_ :. zi~^ :■£: 
oxygen, while animals absorb oxygen and give off carbon 
dioxide. Bnt it has since been f onnd that no such differ- 
ence exists^ bnt that the process of respiration is iden- 
"z ::■.— --r -zzze iz. cezz. Tie zztItI:- Lie-= in -'_7 z:-:: 
that the green plants have the added work of photosyntax, 

All these chemical changes concerned in the process :z 
zzl:z:tl:z_ :z ~_e " :_:-zz • 17 :rjr ± : ;-;--_ -— --■ -_-. Lr-r '::■'. 
zerzz "".-".::; _-'"'. >ee ^";zt -. _:- z_-~; :■< :ziszz is :z 
-::::. .5. 1 : : z--r;: _ :~e. — _i;-. ::::_".: _-- ~z:--e :L;z ± t- 
"--::-: ""..:. - ~\~ : ~zz _: : ;~t = . ~~:z — :zi: z: -izz _- ::--. 
i— ■! _ .7-"'.".' .:"i~t. ~zz_:„ i- "_r :t~~-_ — :i _ ._t former. 
(See diagram page 58.) 

89. Transpiration- — A fonrth function of the leaf of 
the plant is transpiratitm. In order to get the food mate- 
rials to the leaves of the plant from the roots 7 more water 
is absorbed by the plant than it can make use of and this 
water is given off to the snrronnding air through the 
stomata by the process of transpiration. This can be dem- 
onstrated by putting the petiole of a vigorous leaf through 
: Terr:r:-~ei i-irToiiri resrirz-L' zm:z_ :• ~zzo:mr ?::miz:zz 
water, and inverting another tumbler over the blade z 
the leaf. The moisture given off by the still vigorous leaf 
will be condensed on the inner surface of the tumbler. 
Tie zmozzz ::' miismre r-~ri :z cy :- -iz_ie i-ror iz. mi- 
experiment will give some idea of the vast amount of 
water given off by field of wheat T a field of corn, or a 
:' mm 

To- emmm :: "mmmrmim mrie? mm me :■ m Tz ~z m 
"•: mzim zm - __-.-„- -> --_; mm .. I* zzmmm i- * m — :z iz 
great quantities, transpiration will be more active T if in 
less -tied quantities the process will be checked. The evap- 
oration is regulated by means of the stomata, which are 
able through their guard cells to open and close ocasion 
requires. Plants in desert conditions would naturally 



LEAVES, CONTINUED 



61 



have but few stomata on small evaporating surfaces, as 
compared with plants in conditions where water was 
abundant. These would have many more stomata and 
greater leaf expanse. 

The fact of importance in connection with transpiration 
is not the mere giving off of the water, but the fact that 
this escaping water is an external indication of work 
going on within the leaf. 

90. Kinds of leaves. — Leaves are of two kinds, 
simple and compound. The simple leaves have the blade 
all in one more or less continuous piece, while the com- 




Fig. 218. Leaves showing pinnate and palmate branching; the one to the left is from 
sumach, that to the right from buckeye. — Caldwell. 

From Coulter's Plant Structures. Copyright, 1899, by D. Appleton & Cc. 

pound leaves have the blades divided into separate divis- 
ions, or leaflets. Most of the leaflets have distinct stalks, 
which are more or less distinctly joined to the midrib. 



62 HOME STUDY— BOTANY 

This last character, together with the complete division of 
the blade into leaflets, characterizes compound leaves, and 
constitutes the main difference between the divided leaves 
and nearly all compound leaves. 

In compound leaves there is to be noted a variation in 
the number of leaflets, and also in the manner of division, 
the leaflets in some being arranged in the pinnate order, 
such leaves being pinnate! y compound, and in the others 
palmately compound. 

The leaves of the cherry, violet, oak, maple, and gera- 
nium, are illustrations of simple leaves. The leaves of the 
rose and honey locust are examples of pinnately compound 
leaves, while the leaves of the clover, sweet buckeye, and 
rue anemone are illustrations of the palmatelv. compound 
leaf. 

91. Special forms of leaves. — Leaves do not always 
do chlorophyll work solely, and to serve other functions 
they sometimes take special forms. 

(1) Bud scales. — Of bud scales we have already 
spoken, and that these are leaves can be shown in many 
plants. "When they first begin to send out new shoots, a 
gradual transition from the outer brown bud scales to the 
green leaves may be seen. 

(2) Tendrils. — For the purpose of carrying its organs 
up to the light and the air, the plant develops a elimbing 
habit and is held and supported by tendrils. These ten- 
drils are modifications of the leaf, sometimes of the whole 
leaf, and sometimes of a single leaflet of a compound leaf, 
as in the case of the sweet pea. 

(3) Spines. — On some plants spines are found which 
the plant has developed to protect it from destruction by 
browsing animals. In the axils of these spines buds are 
borne, and this shows that the spines are really leaves. On 
some shoots of the barberry, spines may be found which 
show a gradual transition from the true leaf to the spine. 

(4) Scale leaves. — The scales or coats of the onion are 
leaves, or the fleshy bases of leaves. Removing the outer 
coats, the inner ones will be seen to bear more or less per- 



LEAVES, CONTINUED 63 

feet leaves at their tips. Subterranean stems, as root- 
stocks and tubers bear leaves in the form of minute scales. 
All these are known to be leaves, because buds can be 
found in their axils, just as in the case of the well devel- 
oped leaves of the plant. 

(5) Flytraps and pitcher plants. — Two remarkable 
plants, the Venus's flytrap and the sundew, have leaves 
peculiarly modified for the purpose of entrapping insects. 
The leaves of the sundew are round, covered with a sweet, 
sticky substance which attracts the insect, and are sur- 
rounded by a circle of tentacles or hairs. When an insect 
alights upon the hairs, it becomes fast in the sticky sub- 
stance secreted by them, and they gradually bend inward 
and press the insect down upon the leaf. Then the leaf 
pours out a digestive fluid and digests and absorbs all the 
soft portions of the insect's body. The Venus's flytrap 
has its leaf blade constructed upon the plan of a steel trap. 
Over its surface are some sensitive hairs and when the 
insect touches these, the halves of the blade shut together 
quickly and capture the insect. After digesting the insect, 
the trap opens for more victims. 

Some plants have leaves developed into tubes or urns 
for the same purpose. These so-called pitchers contain 
some water at their base, and have various means of 
attracting insects and causing them to fall into the water 
where they are drowned and afterward digested. The 
reason for these peculiar modifications is that these plants 
live in regions poor in nitrogen and other proteid ele- 
ments, and as the soft parts of the insect bodies are mainly 
proteids, they have adapted themselves to this means of 
supplementing their scanty food supply. 

QUESTIONS 

1. What is the epidermis of a leaf ? What are 
stomata ? What is their use ? What are guardian cells ? 

2. What can be said of the number of stomata on a 
leaf ? What is the advantage of the small size of the 



64 HOME STUDY — BOTANY 

stomata? State some ways in which the opening is pro- 
tected. 

3. What does the small picture on page 53 show? 

4. In the illustration on page 54 have you traced 
out carefully every feature presented ? 

5. What and where are the palisade cells of a leaf ? 
What are the intercellular spaces ? How formed ? 

6. What is the particular function of each part of 
the leaf ? 

7. What is venation ? What are the veins of a leaf ? 
What is pinnately netted veining? Palmately netted 
veining ? Pinnately parallel veining ? Palmately parallel 
veining ? 

8. Have you studied carefully the picture on page 56 ? 

9. What is the relation of all the green parts of a 
plant to the plant body ? When can the work of the leaf 
best be accomplished ? How is this demonstrated ? 

10. Why are green plants able to live without help 
from other organisms ? What is meant by the power of 
organization in green plants ? 

11. What are the materials required by the plant? 
Where and in what form does it obtain them ? Why can 
these substances be used only in the form of a gas or 
liquid ? 

12. What does the plant clo with these inorganic com- 
pounds ? What is a carbohydrate ? 

13. What is photosyntax? What is the mechanism 
for the work of photosyntax? Why must green plants 
have good leaf exposure ? 

14. Of what use are the carbohydrates in the nutri- 
tion of the plant ? What are proteids? Are they depend- 
ent upon light for their formation ? 

15. What is digestion in the plant body? What is 
assimilation? What is the object of each of these proc- 
esses ? 

16. What is illustrated by the diagram on page 58? 

17. How does the plant obtain energy for all its work ? 



LEAVES, CONTINUED 65 

What is oxidation ? What effect is produced upon the 
protoplasm by oxidation ? 

18. When does the plant respire? What is the com- 
parison to be made between photosyntax and respiration ? 

19. What is to be said of the process of respiration in 
plants and animals ? In what lies the real difference 
between green plants and animals ? 

20. What is metabolism ? What is constructive metab- 
olism ? Destructive metabolism ? 

21. What is transpiration? How is it accomplished 
in the plant body ? What is the source of the water ? 
By what part of the plant body ? What can be said of the 
amount of moisture thus given off by plants ? 

22. Upon what does the amount of water transpired 
depend ? What is the fact of greatest importance in con- 
nection with transpiration ? 

23. Name the kinds of leaves. What is a simple leaf ? 
What is a compound leaf ? What is the chief characteris- 
tic of compound leaves ? How are they distinguished 
from divided leaves ? 

24. What are pinnately compound leaves ? Palmately 
compound leaves ? 

25. What other trees would show equally well the 
peculiarities illustrated by those in the picture on page 61 ? 

26. What are bud scales ? Tendrils? Spines? Scale 
leaves ? 

27. What are flytraps and pitcher plants ? Why do 
these plants possess these peculiar modifications ? 



LESSOR VI 

THB FLOWER 

The flower produced by plants is a stem, modified to 
perform a function different from that of ordinary stems. 
The object of the flower is to produce the seed, in order 
that the plant may reproduce its kind. 

92. The parts of a flower. — The early trillium is 
an excellent flower for type study, but as it blooms only 
in early spring is not a very convenient example. The 
cultivated geranium may be used in its stead, but this 
flower is open to the objection that cultivation has brought 
about an alteration of some of the parts and several 
bunches of the flowers may have to be studied in order to 
see all the parts in perfection. 

Beginning with the outermost part of the flower, a 
whorl of green leaf-like bodies may be made out. This is 
the calyx, said the separate divisions are sepals. The 
inner whorl of the flower, the colored part, is the corolla 
and the parts the petals. The calyx and the corolla 
together constitute the floral covering, or perianth. 

Removing some of the petals and sepals without dis- 
turbing the remainder of the flower, two more sets of 
organs may be seen. The first of these sets consists of a 
whorl of stalked, narrow bodies, called stamens. Each 
stamen consists of two parts, the smooth stalk or filament > 
and the yellow, two-lobed body on the filament, the anther. 

If the anther is not too old, its parts may easily be dis- 
tinguished. A green extension of the filament lies along 
one side of the anther, this is the connective. The two 
large yellow lobes, between which the connective lies are 



THE FLOWER 



67 



called the cells of the anther, and these cells are filled 
with a yellow, more or less cohesive substance, the pollen. 
Under the microscope this is shown to consist of spherical 
bodies called pollen grains. In the older anthers it may 
be seen that the cells have broken open and have allowed 
the pollen to escape. 

The innermost organ (sometimes several, sometimes 
but one) is the pistil. This consists of an enlarged por- 




Fig. 200. A flower of peony, showing the four sets of floral organs: Jc, the sepals, to- 
gether called the calyx; c, the petals, together called the corolla; a, the numerous 
stamens; g, the two carpels, which contain the ovules.— After StrasburgEr. 

From Coulter's Plant Structures. Copyright 1899, by D. Appleton & Co. 

tion, the ovary, above this a slender stalk, the style, and 
upon this a structure having a number of divisions, the 
stigma. 

With a sharp knife make a transverse section of the 
ovary, and note that it is divided into a number of com- 
partments or cells. In each one of the cells are several 
rounded bodies, the ovules, and these ovules are attached 
to a portion of the inner area of each cell termed the 
placenta. 

The ovary is the part of the flower which develops into 
the fruit and the ovules develop into seeds. But the 
ovules will not so develop unless fertilized. The process 
of fertilization will be described further on in the work. 



- - - - 



- HOME 5 T.DT— BOTANY 

A" the parts of the flower are borne upon the end of 
the stem, "which is more or less enlarged for their recep- 
tion, and is then called the receptacle. 

■-'o. Variation in floral organs. — Tie £:r::.L •:rg^= 

£■::—. :ex~.ire ai: ~; ::i. ZLe~e ~ur:a::-:z~ i-in :e :zl" 
briefly indicated here. Many of the terms given are self- 
explanatory, in other cases, Webster's dictionary "will 
give their botanical meaning. 

(1) Calyx. — The sepals of the calyx may be distinct, 
as in the geranium, then the calyx is said to be polysep- 
alous. When the sepals are united as in the fuchsia, the 
calyx is momosepahms or gamosepalous. The sepals in 
different flowers vary much as to form, color, texture and 
±e like. 

. — The corolla, like the calyx, is polypet- 
lous (gamopetalous). The variations 
in the form of the corolla are more numerous and striking 
than in the calyx. The corolla may be tubular, funnel- 
form, bell-shaped, labiate, salver-shaped, rotate, papiliona- 
ceous, etc The petals may be placed on the receptacle 
(hypogynous) or upon the calyx (perigynous). 7 - 
number, color, and shape, of the individual petals also 
varies greatly. 

(3) Stamens. — The number and length of the stamens 
vary, and they are said to be opposite or alternate in their 
position with reference to the parts of the corolla. They 
may be placed upon the calyx (perigynous), the petals 
(epipetalous), or the receptacle (hypogynous). 

Sometimes the stamens are united by their filaments 
(monadelphous, diadelphous, etc) or they may be united 
by their anthers (syngenesious) or may be distinct. The 
attachment of the anther to the filament is innate, adnate, 
or versatile. The pollen of the anther is spoken of in 
regard to the color and abundance The filaments are 
described in regard to length, form, surface, and color. 

(4) Pistil. — The stigmas and styles are described 
regarding number, form, color, surface, division. 



THE FLOWER 69 

The ovaries vary as to the number, size, form, surface, 
and position. The ovary when free from the calyx is 
said to be superior, when united with the calyx, so that 
it seems to project below it, it is said to be inferior. In 
a cross section, the ovary may be found to vary in regard 
to number of cells, placentae, and number and size of 
ovules. The placentae are parietal, axile, or free central, 
accordingly as the ovules are attached (1) to the outer 
walls of the ovary, (2) the inner angles formed by parti- 
tions, or (3) on a central axis which is not united by parti- 
tions with the outer walls. 

If there is but one cell, one placenta, one style, and one 
stigma, the pistil consists of but a single carpel or pistil 
leaf, and is said to be a simple pistil. If there are two or- 
more cells, placentae, styles, or stigmas, the pistil is made 
up of more than one carpel and is compound. 

94:. Variation in flowers. — When a flower has both 
stamens and pistils, it is a perfect flower. If in addition 
to these it has both calyx and corolla it is a complete 
flower. If the sepals are equal in form and size, and the 
same is true of the petals, the flower is a regular flower. 
Flowers may be -imperfect, incomplete and irregular. 

One of the most common and most puzzling ways in 
which a flower may be incomplete is to have the corolla 
lacking. In some flowers, as in the lily, the floral envel- 
opes are all alike, all being uniformly large and brightly 
colored. This is generally termed a perianth. In other 
flowers both floral sets may not appear, and in that case it 
has become the custom to regard the missing set as the 
corolla, and call the remaining one the calyx, even though 
it is large and very brightly colored. Such flowers are 
called apetalous. It is not always possible to tell whether 
a flower is apetalous, or is simply one whose perianth has 
not yet differentiated into calyx and corolla. Often in a 
perianth the position of the parts is like that of a calyx 
and a corolla, while in an apetalous flower there is no such 
regularity of position. 



TO HOME STUDY — BOTANY 

Occurring very frequently are flowers having' either 
starnens or pistils lacking. Upon a single plant may be 
found flowers having' only stamens, others having only 
pistils. These flowers are called staminate and 'pistillate. 
They may occur upon the same plant, as in the elm, or 
upon entirely separate plants of the same species, as" 
in the willow. Those plants which have both kinds are 
called monoecious (of one household) ; when flowers are 
upon two separate plants, they are said to be dioecious 
(of two households). 

95. Inflorescence. — Flowers are usually borne near 
the top of the plant, since the plant must grow before it 
can bloom. Often they are produced in great numbers. 
The result is then that the flowers often must stand very 
close together, forming a cluster. 

Certain definite or well marked types of flower clusters 
have received names, but the flower clusters which per- 
fectly match the definitions are the exception rather than 
the rule. Some of the more common forms of clusters are 
the raceme, spike, head, catkin, corymb, umbel, and cyme. 
Examples of these in order of their mention are, lily of the 
valley, mignonette, clover, pussies of willows, bridal 
wreath, carrot, and apple. 

The mode or method of flower arrangement is known 
as the inflorescence. The inflorescence may be either clus^ 
tered or solitary. 

96. The essential organs.' — The stamens and pistils 
are both directly concerned in the production of the seed 
and so are called the essential organs of the flower. Some 
plants consist of but the two sets of organs, without any 
of the floral envelopes. 

97. Nonessential organs. — The calyx and carolla are 
considered the nonessential organs as they are not directly 
concerned in the production of the seed. But they have 
several important uses, such as serving to protect the essen- 
tial organs in the bud, and may also, when fully developed, 
by their form, size, and position, protect the essential 
organs against rain, wind, and undesirable insect visitors. 



THE FLOWER 71 

A third use of these organs is in connection with the 
process of pollination. In order that an ovule may be 
fertilized the pollen of the flower must be transferred to 
the stigma, of a different flower usually. Insects are often 
the agents by which the transfer is accomplished, and the 
bright color of the nonessential organs serves as an attrac- 
tion, while their form, size, and arrangement may be such 
that insects of this kind will find a resting place while at 
work. 

OS. The flower a modified branch. — That the flower 
is a branch may be shown by several facte. 

(1) It develops from a bud which is at first indis- 
tinguishable from a leaf bud, and may be either axillary 
or terminal in its location as is the leaf bud. 

(2) The parts of the flower are modified leaves. In 
many flowers as the cactus, there is often a perfect gra- 
dation from small leaves through sepals to petals. Sepals 
and petals also often resemble leaves in form and vena- 
tion, and the sepals also have the color and function of the 
leaf. 

The stamens and the pistils may be proven to be greatly 
modified leaves, in such flowers as the double rose, the 
white water lily, or the peony. Here some of the stamens 
are partly developed into petals, in the water lily the 
gradation is often perfect. In many double flowers all 
the stamens generally have become petals. The structure 
of a stamen is not unlike that of a leaf; the filament corre- 
sponds to the petiole, the connective to the midrib, the 
cells of the anther to the two halves of the blade. 

The structure of a pistil is also like that of a leaf folded 
and united at the edges. The style corresponds to the 
tapering apex, the tip of which forms the stigma. 

(3) All the parts of the flower sometimes revert to 
true leaves. This is seen in the case of the green blossoms 
of the strawberry. 

(A) In rare instances buds develop in the axils of the 
parts of the flowers, as they do in axils of leaves, and 



72 HOME STUDY — BOTANY 

leafy branches or flowers will grow out of the flower. The 
geranium often exhibits such a phenomenon. 

99. Fertilization.— By fertilization in seed plants the 
botanist means the union of a generative or male cell from 
the pollen grain with an egg cell, which is found in the 
ovule. (See page 21.) This gives rise to a cell which 
contains material derived from the pollen grain and from 
the egg cell. 

An ovule is a body with a stalk which fastens it to some 
portion of the cell of the ovary. Entrance to the interior 
of the ovule is obtained through an opening at one end. 
Inside is the embryo sac and inside this, at the end near- 
est the opening, is the egg cell or oosphere. 

Each pollen grain is a cell, with distinct cell walls, and 
a dense nucleus, imbedded in the protoplasm. 

The pollen grain is deposited upon the sticky stiginatic 
surface, by various methods which will be described in the 
next lesson. Shortly after its deposition it germinates, 
that it, the outer wall breaks and the contents, including 
the nucleus, are pushed out in the form of a slender pollen- 
tube. 

This pollen tube penetrates the tissue of the style, goes 
into the cavity of the ovary, enters the opening of the 
ovule, then penetrates the wall of the embryo sac, where 
the oosphere awaits it. While the pollen tube has been 
lengthening, its nucleus has divided into two nuclei, and 
when the pollen tube comes in contact with the oosphere, 
one of these nuclei unites with the oosphere, and the' latter 
is fertilized, and an oospore is formed. 

This oospore now grows by cell division, developing 
into the embryo plant which is found within the seed. So 
a seed is not a simple reproductive body, but is a very 
complex structure, containing the beginnings of all the 
plant structures, together with more or less nutritive mate- 
rial for the nourishment of the embryo when it first begins 
to grow and is unable to obtain nourishment from the sur- 
rounding medium. 



THE FLOWER 73 

The length of the pollen tube varies with the length 
of the style, and the length of time it takes the tube to. 
grow also varies considerably. In some cases it requires 
twenty-four hours or more, in others, notably those plants 
having very long styles, the process requires from one to 
three days. But no matter what the length of the style 
may be, nor what the length of time may be, the process of 
fertilization must be accomplished essentially as described 
above, or there will be no seed. 

The necessary feature in fertilization is the union of 
the essential contents of two cells to form a new one from 
which the future plant is to spring. It will be remem- 
bered that this kind of union was found to occur in the 
lower plants, resulting in the production of a spore capable 
of growing into a new plant like that which produced it. 
(See page 8.) 

It will be noticed that nearly every plant produces a 
vast number of pollen grains, when compared with the 
number of seeds which finally result, or with the number 
of ovules. Only one pollen grain is necessary to fertilize 
each ovule, but so many of them are lost in the transfer 
from anther to stigma, that in order to provide for the 
propagation of the plants, they must produce many more 
of pollen grains than of ovules. The ratio varies greatly, 
from being as low as 8 grains to an ovule, to as high as 
7,000 to 1, and in some plants even much greater. The 
differences depend upon the way in which the pollen is 
carried from the stamens to the pistil. 

100. The seed.: — The seed, it has already been stated, 
is a development of the ripened, fertilized ovule. The 
seed contains the miniature plant or emhryo. 

The outer coating of the seed is called a testa, and this 
hermetically seals the structure within so that develop- 
ment and activity are checked, and the seed rests until 
it is placed under favorable conditions for germination. 
This testa is variously developed in seeds, sometimes 
smooth and glistening, sometimes rough. Sometimes it 



74 HOME STUDY — BOTANY 

develops prominent appendages which . aid in seed dis- 
persal, as the tufts on the seed of the milkweed and cotton. 

The embryo usually has three parts which have received 
names: (1) the little stemlet or hypocotyl, whose pointed 
end is the root tip, (2) the seed-leaf or cotyledon (usually 
one or two, and (3) the bud or plumule lying between the 
cotyledons. These parts are well seen in the common 
bean, particularly after the seed has been soaked for a 
few hours. 

Every seed is provided with a greater or less amount 
of food for the nourishment of the germinating plant. 
The most common form of this food is starch. This food 
may be stored in the large, thick cotyledons, as in the bean, 
or it may be outside the small cotyledon, as in the Indian 
corn. 

The vitality of the seed varies greatly. Some seeds 
maintain life but a short time, a few weeks or even days, 
and others will maintain it for years. 

101. Germination of the seed. — When the embryo 
plant is supplied with moisture, warmth, and air (oxy- 
gen) it is aroused from its dormant state and grows. It 
does not truly germinate, for germination started when 
the oospore was formed, but it was checked during the 
resting time of the seed. The embryo lives for a time on 
the stored food and gradually the little plant secures a 
foothold in the soil and gathers food for itself. 

The first part of the young plant to emerge from the 
seed is the tip of the hypocotyl, which is to develop the 
root system. Shortly after, the stem tip arises from the 
seed, and bears with it to the light the cotyledons and the 
first pair of true leaves which formed the plumule in the. 
seed. The cotyledons do not emerge from the seed in all 
cases. From the very beginning of the emergence of the 
plant from the seed, the root tip seems to be very sensitive 
to the earth influence and also to moisture influence, for 
no matter what the position of the seed may be, a curva- 
ture is developed which directs this tip towards and into 
the soil. And likewise the stem tip is very sensitive to 



THE FLOWER 75 

light influence, being guided in a general way towards the 
light. 

QUESTIONS 

1. What is the flower of a plant? What is its func- 
tion ? 

2. What is the calyx ? What are sepals ? What is 
the corolla ? What are petals ? What is the perianth ? 

3. What is a stamen ? What are the parts of a stamen ? 
What are the parts of the anther ? How does the pollen 
get out of the anther ? 

4. Have you studied the excellent illustration of the 
parts of a flower shown on page 67 ? 

5. What is the pistil ? What are its parts ? What 
are the parts of the ovary? Into what does the ovary 
develop ? Into what do ovules develop ? When do they 
so develop ? What is the receptacle ? 

6. What are the variations to be found in the calyx? 
In the corolla ? In the stamens ? In the pistils ? 

7. What is a simple pistil ? A compound pistil ? 

8. What is a perfect flower ? A complete flower ? 
A regular flower ? An imperfect flower ? An incomplete 
flower ? An irregular flower ? 

9. When a flower has but one set of floral envelopes, 
which is the one that is lacking ? What is an apetalous 
flower ? What is the difficulty in recognizing an apetalous 
flower ? 

10. Why are flowers usually borne near the top of the 
plant ? Why are they often in clusters ? 

11. What is inflorescence ? What are the main classes 
of inflorescence? 

12. What are the essential organs of the flower ? Why 
are they essential ? What are the nonessential organs ? Do 
these nonessential organs have any use ? 

13. What are some of the facts that prove the flower 
to be a modified branch ? 



76 HOME STUDY — BOTANY 

14. What is meant by fertilization in seed plants ? 
What is the structure of the ovule ? What is the structure 
of a pollen grain ? 

15. Why is the pollen grain deposited upon the stigma 
of a flower ? What becomes of it wh^n so deposited ? 

16. What is a pollen tube ? What is the oosphere ? 

17. How does the pollen tube come in contact with the 
oosphere ? When is the oosphere fertilized ? What is 
then formed ? 

18. How and into what does the oosphere develop ? 
What is a seed ? How does a seed compare with a spore ? 

19. Upon what does the length of a pollen tube 
depend ? 

20. What is the necessary feature in fertilization? 
Where else was this same process noted ? 

21. Why does a plant produce usually so vast a num- 
ber of pollen grains ? 

22. What is the embryo of a seed ? 

23. What is a testa? What is its function? 

24. What are the parts of the embryo ? 

25. What is the use of the starch and other food mate- 
rials in the seed ? 

26. What is necessary for the germination of the seed ? 
When does germination really begin ? 

27. What are the steps in the early development of 
the young plant ? 



LESSON VII 

SPERMATOPHYTES 

102. Angiosperms and gymnosperms. — In the follow- 
ing pages, not much more than a mere statement of the 
main characteristics of this great group can be given. 

The main points of distinction between the two great 
classes of Spermatophytes, the angiosperms and the gymno- 
sperms, has been expressed in the statement that the 
gymnosperms bear naked seeds, while the angiosperms 
have the seeds in some form of a closed ovary. A pine 
cone and the pod of a bean will illustrate this. The cone, 
in the sense that it is a product of the changes brought 
about by fertilization, is the fruit of the pine and is made 
up of a number of scales. Each of these scales bears at its 
base, two seeds which are attached to the surface of the 
scale, but have no envelope about them. In the bean the 
walls of the fruit make a sac in which the seeds of the 
plant are completely inclosed. 

103. Gymnosperms. — The gymnosperms are the older 
class of the Spermatophytes, and occupied a much more 
important position in the earlier geological periods, form- 
ing a characteristic feature of the luxuriant vegetation of 
the coal measures. They are now reduced to a few hun- 
dred species. Being the older class, they exhibit a much 
closer alliance with the Pteridophytes than do the angio- 
sperms. They are all woody plants, with secondary 
growth in thickness, but differ widely in habit. Some are 
tree forms, others shrubby, and some are high climbing- 
vines. The leaves are simple, and are then usually needle- 
like, as in the pine, or scale-like, as those of the arbor 
vitae, or they may be pinnate as are those of the cycads. 



78 HOME STUDY -BOTANY 

The flowers of the gymnosperms are characteristic 
organs. These are of two kinds, staminate and pistillate, 
and the plants may be monoecious or dioecious. The 
inflorescence is cone-like in general structure, the pistil- 
late being more distinctly so. The ovules are naked and 
are borne in the axils of the scales of the young pistillate 
cone, and have no style or stigma. The seed into which 
the ovule develops is usually winged. 

The staminate flowers are simple stamens borne under 
scales which form small yellow catkins. After shedding 
the pollen, the catkins soon fall. The pollen is dry, very 
abundant, and each grain bears two little wings to help 
in its transportation through the air. The pollen is borne 
to the pistillate flowers by the wind, and slides down the 
scale to the ovule, where it lies in drifts. The pollen 
tubes then develop and entering the opening in the wall of 
the ovule, unite their nuclei with the oosphere and fer- 
tilization is accomplishd. The pistillate cone persists 
upon the tree, and its scales become very hard. While the 
ovule is developing the scales of the cone close over it, but 
when it has ripened into a seed the scales open again and 
permit the seeds to fall out, 

104. The groups of gymnosperms. — The most impor- 
tant groups of the gymnosperms are the cycads and conifers 

(cone bearers). The cycads are exclusively tropical and 
are found in both the western and eastern hemispheres. 
They resemble tree ferns in their general appearance, 
structure, and dimensions, but their distinctive character- 
istic, and the one which places them with the gymno- 
sperms, is the production of naked seeds. There are but 
eighty species of the cycads in existence now, but in the 
earlier geological times they grew in large numbers and 
formed a large part of the vegetation of all zones, as 
proved by their fossil remains. 

105. The conifers. — The conifers are strictly temper- 
ate in their distribution, and are found in both the north 
and south temperate zones. The genera are unlike in the 
different zones, the most characteristic one of the north 



SPERMATOPHYTES 79 

temperate is pinus, in which all our pines are grouped. 
The species of conifers are comparatively few in number, 
but the number of individuals is so great that great forests 
are formed in these regions. 

In the group of conifers are found besides the pines, the 
spruces, cedars, cypresses, firs, yews, and larches. The 
group is generally known as evergreens, but some of them 
are not really evergreen, the common larch or tamarack 
drops its leaves at the approach of winter just as do most 
of the angiosperms. 

In this group are found some of the largest trees in the 
world, the giant redwoods or sequoias of California. These 
grow to an enormous height and are excelled only By the 
eucalyptus of Australia. Many of the sequoias are from 
fifteen to twenty centuries old. 

The fruits of conifers are not all alike, those of 
the cedars seeming not to have the cone-like structure, but 
close examination of the fleshy berries will show that they 
are made up of scale-like bodies, enveloped in fleshy cover- 
ings. On some of the conifers the fruit is reduced to but 
a single scale. 

106. Angiosperms. — These are the most highly devel- 
oped of all plants, and have formed the chief part in the 
vegetation of the later geological ages. The two great 
groups of this class are the monocotyledons and dicotyle- 
dons. (See page 34.) These two groups exhibit several 
contrasting characters which are always stated to dis- 
tinguish the groups. 

The monocotyledons have but one cotyledon or seed leaf, 
the stems have the bundles scattered irregularly through- 
out and have no annual increase in diameter, and the 
leaves have what is known as the closed system of veining. 
The dicotyledons have two (or more) cotyledons, have the 
bundles in the stem arranged in definite rings, the stems 
have an annual increase in diameter, and the leaves are 
netted-veined. 



80 HOME STUDY -BOTANY 

In the monocotyledons the flowers are usually in 3's, 
that is the sepals, petals, stamens, etc., are three, or some 
multiple of three in number. In the dicotyledons the 
majority of the flowers are in 5's, though some of the 
important orders have flowers in 4 ? s or 2's, or even 3's. 

The system of veining in the leaves of these two groups 
was once distinguished as parallel-veined for the mono- 
cotyledons, and netted-veined for the dicotyledons. But 
many of the monocotyledons, particularly the tropical 
species, have netted-veined leaves. But all monocotyledon- 
ous leaves, whether netted or parallel veined, have a large 
vein running around the edge of the leaf which catches up 
all the small veins and prevents them from running out 
to the edge of the leaf. This is the closed system. In the 
dicotyledonous leaves, the veins run out to the edge of the 
leaf, and the edge is more or less irregular. But of the 
characters stated above, no one of them is absolutely dis- 
tinguishing except the first. 

107. Monocotyledons. — This is the older group of the 
angiosperms and is the less highly organized of the two. 
Several of the families of this group are world wide in 
their distribution. These are the ones that have suc- 
ceeded in adapting themselves to every condition. Four 
of these families form about one-half of the twenty thou- 
sand species of monocotyledons. They are the grasses, 
sedges, lilies, and irises. The distribution of these is 
fairly uniform, that is, there is a natural massing toward 
the tropics. Two species in the temperate to three in the 
tropics represents a natural distribution. The monocoty- 
ledons of the temperate regions are never of large size, but 
many of those of the tropics, as the palms, often form 
large trees. 

Some of the families of this group are of great economic 
importance. The grasses include some of our most impor- 
tant cereals, as wheat, rye, oats, barley, corn, the sugar 
canes, the bamboo, and our pasture grasses, all of which 
are of immense value. Some of the lily family are culti- 
vated as vegetables, for example the onion, and asparagus. 



SPERMATOPHYTES 81 

108. Dicotyledons. — The dicotyledons are the greatest 
of all the groups of plants, both in rank and numbers. 
Nearly all botanists divide them into three divisions based 
on floral characters. These are the apetalous, the poly pet- 
alous and the gamopetalous divisions. The first contains 
the flowers having no corolla, the second, the corolla with 
separate petals, and the third, the petals all united in one 
piece. A new grouping has been made by more modern 
authors into archichlamyclese and sympetalge. The first 
includes the apetalous and polypetalous divisions, while 
the gamopetalous division is placed in the second group. 
The archichlamydeaB contain about one hundred sixty fam- 
ilies while the sympetalse have about fifty. 

The archichlamydese contain about forty thousand 
species, many of which are tree forms. There is no fam- 
ily having a world wide distribution in this group, but it 
is predominantly tropical. The leguminosse, the order to 
which the bean and pea belong, is the greatest order of 
the group. 

The sympetalse also contain about forty thousand 
species, mostly of the smaller forms of seed plants. Three 
great world families are found here, these are massed 
chiefly in temperate zones, but found also in the tropics 
and arctic zones. They are the composites, the mints, and 
the plantains. 

Xo study of the different families of this group and the 
individuals comprising them can be given in this course. 
That must be a matter of individual work, gained by an 
actual study of the plants together with some good guide 
for plant analysis. 

109. Classification. — The classification of plants is 
based upon their actual relationships to each other. In 
each of the four great groups already mentioned (see 
page 5) there are placed those plants which show points 
of great similarity but at the same time have marked 
differences from the group above or below them. This can 
be illustrated by the following outline: 



82 HOME STUDY — BOTANY 

(1) Thallophytes, all haYe a thallus, but no arche- 
gonia. 

(2) Bryophytes, all haYe archegonia, but no woody 
structure. 

(3) Pteridophytes, all haYe woody structure, but no 
seeds. 

(4) Sj:>ermatophyteS; all haYe seeds. 

110. Cryptogams and Phanerogams. — The first three 
groups are classed under one head as Cryptogams, a term 
meaning hidden sexual reproduction, while the plants of 
the remaining group are called Phanerogams, meaning 
evident sexual reproduction. Professor Coulter of Chi- 
cago University states that the names should be reYersed, 
for the sexual reproduction is much more eYident in the 
Cryptogams than it is in the Phanerogams. These great 
groups are sometimes called the flowerless and flowering 
plants, but here also Professor Coulter states that the 
terms are incorrect, for in the popular sense all Spermato- 
phytes do not haYe flowers, and in another sense the spore 
producing organ of the Pteridophytes is a flower. 

111. Flower grouping. — To follow out the idea of fur- 
ther classification in each group we will take the Sperma- 
tophytes for illustration. EYen those who haYe neYer 
made a studY of botanY haYe undoubtedlY recognized the 
fact that all the plants with which they are familiar in 
a general way are not alike, but are readily associated into 
groups. The botanist groups these Spermatophytes first 
into two great classes, gymnospernis and angiosperms. The 
gYmnospernis are the plants bearing naked seeds, while 
the angiosperms haYe the seeds inclosed in a pod or cover- 
ing made of the walls of the OYary. Each of these cla?^? 
is diYided into seYeral great groups. Under the gymno- 
spernis we find the eyeads and the conifers or cone bearing 
trees, and other groups. Under the angiosperms are the 
groups of monocotyledons and dicotyledons. 

The following table will represent the classification - 
far as we haYe now carried it : 



SPERM ATOPHYTES 83 



(Thallophytes. 
I 
Cryptogams-^ Bryophytes. 
I 
tPteridophytes. 



rr- \ Cycads. 

fGymnosperms \ c * nifers> 

Phanerogams] Spermatophytes< 

! a„.,;~<.^,™c. ] Monocotyledons. 
Ungiosperms -> Uicotyle dons. 

112. Order. — Taking the dicotyledons as a basis for 
further grouping, we find that all the plants here may be 
placed in a number of large groups, these we call orders. 
For instance the strawberry, apple, rose, plum, and peach, 
are all distinctly related to each other, so we place them 
in the order rosacea?. The sunflower, daisy, and dog 
fennel, are examples of plants related to each other in 
another way and these are placed in the order compositse. 

113. Family. — Each order may now be grouped upon 
a basis of certain related facts into families. For instance 
the order sapindacese to which our maples belong, is 
divided into the bladdernut family, the soap berry family 
and the maple family. Many authors will still give the 
order and the family as interchangeable terms, but the 
general tendency in later times is to consider the order as 
a more general, and the family a somewhat more specific 
term. 

114. Genus, species, variety. — In the family also dif- 
ferent groups may be made of plants possessing more 
closely related characteristics, and each of these groups will 
be called a genus (plural genera). It is well to state that 
orders may contain one family, and a family may some- 
times have but one genus. The individual members of a 
genus will not resemble each other in every particular and 
these individuals make up the species. If one species 
varies from another in a slight degree we may have a 
variety. 

For illustration of these points we may take the order 
violacese, which has but one family, the violet family, and 
one genus viola. Under the genus viola are a number of 
different species, as the common blue violet (Y. palmata 
L.) the birdfoot violet (Y. peclata L.) the pansy (Y. tri- 



84 HOME STUDY — BOTANY 

color L.). The common blue violet exhibits some varia- 
tions and this is classed as a variety, viola palmata, variety 
cucullata, Gray. After the scientific name of the flower 
often comes the abbreviation of the name of the botanist 
who is authority for it, as in viola palmata L., the L. 
stands for Linnaeus. 

The following outline will show the remaining points 
in classification : 

f Species. 
I Viola Palmata, 
( Violet ( Genus -{ Viola Palmata, 
f Order Violaceae. < < var. cucullata, Gray. 

| ( Family ( Viola ^ Viola tricolor. 

Dicotyledons • -J Order Rosaceae. 
I 
L Order Compositae. 

These points are usually written in the following form : 
f Order — Yiolacese. 
Family — Violet . 
Genus — Yiola. 
Species — tricolor. 
Scientific name — Yiola tricolor. 
Common name — Pansy. 

It will be noted that the scientific name of a plant is 
a combination of the generic and the specific name, and 
that the specific name is never written with a capital, 
although the other designations very frequently are so 
written. 

Different authorities will be found to vary greatly upon 
minor points in classification, but the general plan will 
always be found to be the same with all authorities. 



-{ 



SPERM ATOPHYTES 85 

QUESTIONS 

1. What are Spermatoplrytes ? What are the two 
great classes of Spermatoplrytes ? What is the main point 
of distinction between them \ 

2. Which class of Spermatoplrytes is the older? Has 
it always possessed the same relative importance that it 
now holds ? 

3. Why do gymnosperms exhibit closer alliance with 
the Pteridophytes than do the angiosperms ? What is the 
habit of the gymnosperms ? What kind of leaves do they 
have \ 

4. What kinds of flowers do gymnosperms have? 
Where are they borne ? Where are the ovules borne ? 
Where are the stamens ? What is the character of the 
pollen ? 

5. How is the ovule fertilized ? What is the cone of 
the gymnosperms ? 

6. What are the most important classes of the gym- 
nosperms ? Why are cycads not classed with the ferns ? 
How does the present number of species of cycads com- 
pare with the number in existence during earlier geolog- 
ical periods ? 

7. Where are the conifers found ? What is the char- 
acteristic genus of the United States ? What can be said 
of the number of species of the conifers ? 

8. What plants aside from the pines are grouped 
under the conifers ? Are the conifers all evergreens ? 
Where do we class the giant redwoods of California ? Are 
they the largest trees of the world 1 

9. How do the fruits of conifers compare with each 
other ? Why do the cedars develop the fleshy coverings ? 

10. What is the rank of the angiosperms ? What are 
the two great classes under this head ? 

11. How do we distinguish a monocotyledonous plant 
from a dicotyledonous plant ? What is the closed system 
of veining? 



86 HOME STUDY — BOTANY 

12. How do the monocotyledons compare in age and 
organization with the dicotyledons ? What families in 
this gronp are world wide in their distribution ? How 
does the distribution and size of monocotyledons in tem- 
perate regions compare with that of tropical regions ? Of 
what economic importance are some of the families of the 
group ? 

13. What is the rank of the dicotyledons? What are 
the three divisions usually made of this group ? What is 
the new arrangement of the group ? 

14. Upon what is the classification of plants based ? 

15. What are Cryptogams ? Phanerogams ? Why are 
they so called ? Why should the terms be reversed ? 

16. What are the great groups of the Spermatophytes ? 
How are they divided ? 

17. What is an order ? A family ? A genus ? A 
species ? A variety ? 

18. How is the scientific name of a plant constructed ? 
What is the meaning of the abbreviation after the scien- 
tific name ? 



LESSOR VIII 

ECOLOGY 

PLANT SOCIETIES. SEED DISPERSAL 

115. Ecology. — One of the more recent developments 
in botany is the detailed study of that portion which has 
to do with the way in which plants get along with their 
plant and animal neighbors. This is called ecology. It 
treats especially of the way in which the plants adjust 
themselves to the nature of the soil and climate in which 
they live. It will easily be seen that much of what has 
been said in previous lessons is really ecological botany. 

116. Plant societies. — Plants, in their distribution 
over the earth's surface, are arranged according to a def- 
inite plan. All plants that can adapt themselves to cer- 
tain conditions of soil, temperature, light, etc., will be 
found grouped together wherever these conditions occur, 
and will form what is known as a plant society. Cat-tails 
often grow in swamps in great number, but among the cat- 
tails and down near the surface of the swamp will be 
found many other species of plants, which adapt them- 
selves to the same conditions. These will form a plant 
society. 

Wherever the same conditions are found, there the same 
species of plants will be apt to occur, or, if not already 
there, will nourish when transplanted from other localities. 
Usually related species of plants are not to be found in the 
same society, because the competition between them is too 
great, so a plant society is most often made up of unrelated 
species. 



88 HOME STUDY— BOTANY 

117. Ecological factors. — But very little is known def- 
initely of the operation of the factors which determine 
plant societies. About all that is known is that the water, 
soil, heat, and light conditions surrounding a plant are of 
vast importance to it, and that it changes its nature as it 
is subjected to these factors in varying degrees. 

Some plants require large quantities of watey, others 
get along with very small quantities. As the first plants 
were aquatic, those doing without water must be special- 
ized forms, which have gradually adapted themselves to 
live with but little water. 

Heat is also a factor of great importance not only as it 
determines the great zones of vegetation on the earth's 
surface, but as it affects local areas. Each plant has its 
own range of temperature, sometimes varied, sometimes 
very much restricted. 

The soil is a very important element in determinino- the 
value of plant life. As soils vary in their ability to 
receive and retain water, in the amount of food which 
they hold for plants, and in compactness, so will the plant 
societies vary, some being able to live upon one kind of 
soil, others on entirely different kinds. 

Plants are sun loving and shade loving as they require 
greater or less amounts of light. Their leaves are arranged 
in such a manner as to present the greatest amount of sur- 
face to the light, and so it becomes evident that light also 
is a great factor in the life of plants. 

Wind should be mentioned as an important factor in 
addition to the ones already cited. In regions where there 
are strong prevailing winds, the transpiration of plants is 
very greatly increased, and so plants must learn to adapt 
themselves to this condition. 

All of these factors are instrumental in determining 
plant societies, but not in the same degree in all localities, 
and so there can be various combinations. Any factor 
might be used as a basis for grouping these societies, but 
for convenience thev are classified in reffard to the amount 



ECOLOGY 89 

of water they require. Grouped with reference to this 
factor in their lives, all plants may be classed as: 

(1) Hydrophytes, or water loving. 

(2) Mesophytes, or plants which thrive best with a 
moderate supply of water. 

(3) Xerophytes, or drought tolerating plants. 

(4) Tropophytes, or seasonable plants which are 
hydrophytes or mesophytes part of the year and xero- 
phytes during another part. 

( 5 ) Halophytes, or salt marsh plants and other species 
which can nourish in a soil impregnated with saline 
matters. 

The greatest difficulty in ecological classification arises 
from the fact that it is very hard to determine just what 
amount of water plants have in a region. The nature of 
the soil, the temperature of the soil and air, and the preva- 
lence or absence of drying winds, fogs and heavy dews 
must be known. So the determination of a plant society 
is not a matter for hasty decision, but requires most care- 
ful study. 

118. Hydrophytes. — Hydrophytes may thus be either 
aquatic or land plants. The aquatic hydrophytes are illus- 
trated by the pickerel weed, the duckweed, and the pond 
lily, while the liverworts, mosses, and ferns are land hydro- 
phytes, preferring damp air and soil. All of these plants 
transpire very freely. 

119. Mesophytes. — Mesophytes make up the majority 
of the wild and cultivated plants of the United States. 
The mesophytic condition is the arable condition. If an 
area is hydrophytic, and is to be tilled, it is drained until 
it becomes mesophytic; if it is xerophytic it is irrigated 
and forced to assume mesophytic conditions. The typical 
mesophyte of the greater part of the United States is an 
annual, since most perennials and biennials pass the win- 
ter in a xerophytic condition. 

120. Xerophytes. — A xerophyte is a plant which can 
get along with a scanty supply of water. To be able to 
endure this condition, xerophytes have developed many 



90 HOME STUDY — BOTANY 

adaptations. The two inain things which a xerophyte 
must be able to do is to store up a considerable amount of 
water and give off but very little. So they have, first of 
all. reduced their surfaces for transpiration. 

Some plants, as the cactus. haYe dispensed with leaYes 
entirely, and haYe made the green eoYering of the stems 
do the work of leaYes. Others haYe been protected from 
losing their scanty supply of water by haYing the leaves 
roiled up with the transpiring surface on the inside. Many 
species which bear leaves shed most of them at the begin- 
ning of the dry season, and remain in a half dormant con- 
dition for long periods. 

The roots and stems of xerophytic plants are usually 
thick and fleshy and commonly contain large amounts of 
water. The epidermis of the leaves and stems is gener- 
ally very thick and thus prevents transpiration. Some 
few xerophytes. as the yeast plant, are able to exist for a 
long time in a thoroughly dried state and will then revive 
on being placed in contact with water under the right 
temperature. 

121. Tropophytes. — These seasonal plants are found in 
regions where there is a decided change of seasons. The 
deciduous trees of our own regions are very good illustra- 
tions, as are also all plants which live over winter by 
means of a fleshy bulb, root or tuber which stores food and 
water underground, as the tulips, peonies, potatoes, car- 
rote, and beets. All these plants have a large transpira- 
tion surface during the summer and prepare for winter 
by the dropping of leaves, or the dying down of herbaceous 
parts above the ground. 

Plants which prepare for existence during the dry sea- 
son, as do those of southern California, are also tropo- 
phytes. 

12'2. Halophytes. — The salt marsh plants and those 
which live in the alkali lands of the west are true halo- 
phytes. Most of these plants have a truly xerophytic 
structure, even though they may live with their roots in 
the salt water. The reason for this is that the presence 



ECOLOGY 91 

of salt iii the water makes it almost impossible for osmosis 
to take place and so the halophytes get very little water. 
The mangrove of Florida is one of the best illustrations 
of halophytes. 

123. Other ecological subjects. — Many other subjects 
are discussed in plant ecology. Some have to do with the 
way in which plants protect themselves against animals 
and other plants ; some treat of the manner in which plants 
disperse their seeds. How plants, are pollinated and how 
they adjust themselves to get the best exposure to light are 
two other great ecological subjects. All these represent 
phases of the plant's struggle for existence, and discuss the 
adaptations which plants have been compelled to assume 
in order that they may successfully compete with their 
neighbors. 

12-1. Seed dispersal. — IsTo one ecological subject is of 
more interest than the manner in which the various plants 
disperse their seeds. A comparatively wide dispersal of 
seeds is necessary with most plants, for by being carried 
away from the neighborhood of the parent plant they get 
%way from competition. Many seeds and fruits are of 
such a character as to increase their chance of wide dis- 
persal. 

125. Adaptations for dispersal. — Seeds are very 
rarely light enough to be carried by the air without some 
special adaptations. These may take the form of inflated 
coats, as in the bladder nut, or they may be appendages, 
such as the wings of the elm, maple, and catalpa seeds, or 
tufts of hair, as illustrated by the thistle, milkweed, and 
dandelion. Another type of dispersal by air is illustrated 
by plants which develop a nearly globular form of the 
plant body when dried, and breaking off near the surface 
of the soil, are blown by the wind for long distances. One 
of the best illustrations of this is the Russian thistle, which 
sometimes scatters two hundred thousand seeds from a 
single plant over a wide area. The tumbleweeds of the 
western prairies scatter their seeds in the same manner. 



92 HOME STUDY — BOTANY 

Certain plants have peculiar seed pods which warp or 
dry unequally and when subjected to even very slight dis- 
turbance, will burst and scatter the seeds. The seeds of 
our common violets, wild geraniums, and jewel weeds are, 
scattered in' this manner. 

Animals of many kinds are very active agents in the 
transportation of seeds. Birds particularly, but other, ani- 
mals also, are attracted by the bright colored parts of 
many fruits. These they eat and either reject the seed 
because of its unpleasant taste, or pass it with the flesh 
of the fruit into the alimentary canal. Many of these 
seeds are so hard as to resist the action of the digestive 
juices and are passed from the canal in a condition suit- 
able for germination. Grapes and junipers are plants 
that are very widely distributed in this way. 

Water birds often carry seeds of many plants in the 
mud which adheres to their feet, and as they are usually 
high and strong fliers they will often carry those seeds 
long distances before depositing them. In two places in 
Iowa the seeds of the yellow lotus, a southern plant, have 
obtained a good foothold, and it is supposed that they were 
brought to the ponds in which they are found by wild 
ducks which stopped there during their spring migrations. 

Other plants have their seeds variously provided with 
hooks, spines, glands, etc., by which they adhere to the 
bodies of animals and are thus carried about. The bur- 
dock, sticktight, cocklebur, and sandbur, are familiar illus- 
trations of these kinds of plants. 

Often seed carrying is purposely done by animals. In 
the other cases they have been unconcious agents, but 
sometimes they carry fruits and nuts to their nests or 
houses to store them for food. Squirrels and blue jays are 
often seen to carry acorns and other nuts and bury them 
for food. Sometimes these deposits are forgotten and thus 
much tree planting is done. 



ECOLOGY 03 

QUESTIONS 

1. What is ecology ? Of what does it treat ? 

2. What is a plant society ? Where will we be likely 
to find plant societies that are similar to each other ? Why 
are not related species of plants f onnd in a plant society ? 

3. What are the important factors which determine 
plant societies ? Why is it important to stndy the water 
supply in determining a plant society? The heat condi- 
tion ? Of what importance is the soil in this stndy ? The 
light? Wind? 

4. Upon what bases are plants classified ecologically ? 
What are hydrophytes? Mesophytes ? Xerophytes ? 
Tropophytes ? Halophytes ? 

5. In what lies the greatest difficulty in determining 
the correct ecological classification of plants ? 

6. What may be the location of hydrophytes ? What 
are some aquatic hydrophytes ? Some land hydrophytes ? 

7. Of what importance are mesophytes in the United 
States ? What is the connection between the mesophytic 
condition and the arable condition of soils ? 

8. What is a xerophyte ? What are the two main 
things which a xerophytic plant must be able to do ? In 
what way have xerophytes adapted themselves to this con- 
dition ? Why are xerophytic plants often leafless ? What 
other changes are made in the amount of leaf surface ? 

9. What is the nature of the roots and stems in 
xerophytes ? Of the epidermis ? Why is the yeast plant 
a xerophyte? 

10. What is a tropophyte ? Where are tropophytes 
found ? What are some of the tropophytes of our own 
region ? 

11. Where are halophytes found ? Why have they 
usually a xerophytic structure ? 

12. What are some of the other subjects discussed in 
plant ecology ? 

13. Why is a wide dispersal of seeds necessary with 
many plants ? Why do some plants have winged append- 



94 HOME STUDY — BOTANY 

ages or tufts of hair upon the seeds \ What manner of 
dispersal is practiced by the Russian thistle ? 

14. How are seeds distributed by explosion of the 
pods ? What plants are illustrations of this method ? 

15. In what way do animals assist in seed distribu- 
tion ? Why are many fruits brightly colored ? How do 
water birds act as agents of distribution ? Why are plants 
often provided with spines, hooks, and glands ? 

16. Is seed carrying ever done purposely by animals? 



LESSON IX 
ECOLOGY, CONTINUED 

POLLINATION. THE LIGHT RELATION 

126. Pollination. — Pollination is the transferring of 
pollen from the anther to the stigma, in order that fertili- 
zation may be accomplished. It was long supposed by 
botanists that the pollen of any perfect flower need only 
to be placed on the stigma to insure fertilization. But 
Charles Darwin in 1857 and 1858 stated, as the result of 
a long series of investigations, that many flowers were 
entirely dependent for fertilization upon the transference 
of pollen from one plant to another. It was also shown 
that in some cases where the plant might produce some 
seed if self pollinated, it would do far better if the seed 
were produced by the pollen from another plant of the 
same kind. 

127. Kinds of pollination. — Pollination may be of 
two kinds, cross pollination and self 'pollination. Cross 
pollination it is supposed is by far the more common 
method, still many plants do bear flowers that are con- 
structed for self pollination. One of the most common 
illustrations of this is the violet. It bears large, conspic- 
uous flowers which are cross pollinated only, but down 
among the leaves will be found small inconspicuous 
flowers, which are supposed never to be open, and these 
produce large numbers of seeds. Flowers of this type, for 
the reason that they were supposed not to open, are called 
clpistocjamous flowers. "Recent investigations have shown 
that cleistogamv is much more common than has been 



96 HOME STUDY— BOTANY 

supposed and is practiced by a large number of flowers, 
aside from the violet. 

A study of the pollination of the yucca and of figs 
(caprification) will give additional facts of interest, 
regarding self pollination. 

In cross pollination it is evident, that as there must be 
a transference of the pollen from one plant to another, 
there must be agents of transference. These are mainly 
wind and insects, though birds, snails, and water are also 
active agents with some particular types of plants. 

Upon the basis of pollination, flowers may be divided 
into groups as wind pollinated and insect pollinated, and 
each group will exhibit its own characteristics. 

128. Wind pollinated flowers. — All the grasses and 
by far the larger number of trees are examples of wind 
pollinated plants. The flowers in these cases are very 
inconspicuous, so much so that school children on begin- 
ning botany are often surprised to learn that the common 
shade trees and grasses have any flowers at all. These 
wind pollinated flowers are usually borne on exposed or 
elevated or lengthened structures, such as long flower 
stalks, or the stamens have very long filaments. 

The stigmas are often very sticky, or are plumed, and 
thus adapted to catch the flying pollen grains. The pollen 
is very dry and light and is remarkable for its great 
abundance. This is necessary because with this method 
of transference so much of the pollen is lost. Everyone 
is familiar with the vast quantities sent into the air by 
our common ragweed. In pine forests the pollen is often 
produced in such abundance as to fall in showers from the 
tree. These shoivers of sulphur are often borne a long 
distance from the woods in which they are produced. 

Wind pollinated flowers are also remarkable for the 
fact that they are usually very regular, and that they have 
no odor and no nectar. In many cases they appear on the 
plant some time before the leaves are developed. 

129. Insect pollinated flowers. — In studying a plant 
from the standpoint of its surroundings no one thing is 



ECOLOGY, CONTINUED 



97 



more remarkable than its relation to its animal neighbors. 
This relation is productive of mutual benefit, for while the 
animal helps the plant to provide for its reproduction, the 
plant furnishes food to the animal. 

In general it may be stated that the showy colors and 
markings of flowers, their peculiar shapes, and their 
odors, all serve as so many advertisements of the nectar 
or the pollen which the flower has to offer its insect vis- 
itors. 





■which may be seen in 1 and 
eve of a moth.— After Gray. 



Fig. 235. A flower of an orchid (Habena- 
ria): at 1 the complete flower is shown, 
with three sepals behind and three pet- 
als in front, the lowest one of which has 
developed a long strap-shaped portion 
(lip) and a still longer spur portion, the 
opening to which is seen at the base of 
the strap, and behind the spur the long 
inferior ovary (epigynous character) ; 
the two pollen sacs of the single stamen 
are seen in the center of the flower, di- 
verging downward, and between them 
stretches the stigma surface ; the rela- 
tion between pollen sacs and stigma sur- 
face is shown in 2 ; within each pollen 
sac is a mass of sticky pollen (pollini- 
um), ending below in a sticky disk, 
in 3 a pollen mass (a) is shown sticking to each 



From Coulter's Plant Structures. Copyright, 1899, by D. Appleton & Co. 

Many insects which visit flowers have smooth bodies, 
but all butterflies, moths, bees, and many beetles, have the 
body more or less roughened or covered with scales or 
hairs, which hold a great deal of the pollen. Often the 
pollen is very sticky and adheres to the body of the insect 



98 HOME STUDY— BOTANY 

until it is brought in contact with the sticky stigma, which 
in such cases, is stickier than the pollen. 

All flowers which depend upon insects to bring about 
pollination have showy colored floral envelopes. These 
colorings are not always brilliant, but enough so to serve 
as an attraction. It has been found that flowers with dull 
yellow, or brownish or dark purple corollas attract flies, 
while red, violet, and blue, are the colors by which butter- 
flies and bees are more readily attracted. White flowers 
often are pollinated by night flying insects, the corollas 
being then very attractive. 

Some recent experiments made upon insects serve to 
prove that many of them are either color blind or are 
very near sighted. If this is true, much of botanical liter- 
ature upon pollination will have to be revised. But it 
has also been proven, that these same insects have remark- 
ably keen scent and thus may be attracted to the flower by 
an odor which human beings are incapable of recognizing. 

It is not to be supposed that the color in the corolla may 
not be of some service. Just what it is is not now known, 
but it may be that color in the flower serves some such pur- 
pose as does the green in the leaves. When we remember 
that these same colors are found in foliage leaves, the sup- 
position does not seem at all improbable. 

Many of the brilliantly colored flowers have very irreg- 
ular corollas. This seems to render the flower more 
attractive and offers at the same time resting places for 
the insects while at the work of obtaining pollen or nectar. 
Sometimes the irregularity is such, as in the case of the 
flowers of the bean family, that the weight of the insect 
in resting upon it will serve to expose the stamens and 
make them come in contact with the insect's body. 

Other brilliantly colored flowers are very regular, but 
in these cases the element of attraction has been consid- 
ered in the grouping in clusters of a number of the flowers. 
The time saved in pollinating a large number of flowers 
in a cluster is of great value to the flower also. The 



ECOLOGY, CONTINUED 99 

clover and nearly all the plants of the composite family, 
the sunflower, and the daisy are illustrations of these facts. 

The odor of cross pollinated flowers is generally very 
noticeable. They are often, but not always, sweet scented. 
The hawthorn is an illustration of the carrion scented 
flowers, but it attracts many insects, nevertheless. The 
night blooming flowers have usually very strongly scented 
corollas. 

Some, but not all, of the cross pollinated flowers have 
nectar elands or lines. These are collections of cells whose 
special function is the secretion of a sweet liquid which 
attracts the insects. This nectar when partially digested 
in the crop of the bee, becomes honey. On the petals of 
many flowers are to be noted lines and groups of lines, in 
striking contrast to the color of the petals. These are 
nectar guides, and followed by the insect, will lead it to 
the nectar secreting portions. 

It is interesting to know that insects do not visit all 
flowers indiscriminately, but that certain flowers and 
insects have been adapted to each other's needs. So that 
sometimes certain families of insects are restricted to 
families of flowers, sometimes to genera and sometimes 
to single species. The orchids are the most highly special- 
ized in regard to insect visits, and they are adapted to 
moths alone. 

130. Hybrids. — Often pollen from one species of 
plant will prove potent upon the stigma of a different 
species. The resulting seed will give rise to a plant which 
combines the characteristics of the parent plants. Such 
a plant is called a hybrid, and this gives a clue to the 
methods used by florists in producing the vast number of 
new varieties of plants. The range of hybridization dif- 
fers very widely in different groups of plants, in some it 
is very wide, in others very narrow. 

131. Protection against unwelcome visitors. — Many 
insects which might visit a plant would be unwelcome 
visitors, for they would eat the pollen or the nectar, and 
be able to carry away but a small amount of the pollen. 

L.ofC. 



100 HOME STUDY— BOTANY 

So plants have adapted means to prevent the entrance of 
these visitors. Some have a sticky ring jnst below the 
flowers, and this forms an effectual harrier against ants. 
and like insects. Others have the calyx tube or stems 
covered with hairs, which may be sticky. 

In some flowers, notably those having nectar at the 
bottom of long spurred petals, the nectar is inaccessible 
except to large, strong insects, which have a tongue or 
sucking tube long enough to reach to the bottom of the 
spur. Other plants have a milky secretion called latex. 
The epidermis in many such plants is very delicate, and 
is very easily pierced by the claws of insects like ants. 
"Whenever the epidermis is so pierced the latex gushes 
out and by its hardening holds the insect fast. 

132. Prevention of self pollination. — It is clear that 
if plants did not have special adaptation to prevent it, 
self pollination would often occur. In dioecious and mono- 
ecious plants it is impossible, but many perfect flowers 
have had to provide certain forms of structure, and other 
peculiarities, to insure cross pollination. Sometimes the 
position of the stigma is such that pollen from the anther 
could not reach the stigma unless carried there. 

In other flowers the stigma and pollen mature at differ- 
ent times. In some of the flowers the pollen matures first, 
and in others of the same species the stigma matures first. 
In other flowers there are stamens and pistils of two sorts, 
one individual has long stamens and short styles, the other 
has short stamens and long styles. And in this case, the 
pollen of the long stamen is active only upon the long 
pistil, while that of the short stamen is potent only upon 
the short pistil. 

133. Bird and water pollinated flowers. — A few 
flowers are bird pollinated, usually those having long, 
tubular corollas, into which the long, bill of the humming 
bird goes in search of nectar. The trumpet honeysuckle 
and gladiolus are instances of this type of pollination. 
Pollen is, in the case of a few aquatic plants, carried from 
flower to flower by the water on which it float?. 



ECOLOGY, CONTINUED 101 

Only a very incomplete idea of pollination can be given 
here, and one cannot gather more than an imperfect 
knowledge of it without actually watching some of the 
flowers and their insect visitors. Any garden will afford 
material for many days' study of this topic, and individual 
flowers should be observed carefully in order to learn their 
particular adaptation to this end. Xo flowers will be of 
greater interest in this stud| r than those shown by our 
common bleeding heart, garden iris, barberry, and dande- 
lion. 

131. The light relation. — All plants with the excep- 
tion of the fungi and a few parasitic plants of other 
groups, must have light in order that they may carry on 
their chlorophyll work. (See page 57.) Some may be 
able to live in strong sunlight, others have learned to adapt 
themselves to shade conditions. It is essential that not 
only the outer portions of the plant be exposed to the ligl#, 
but that every leaf blade, every portion of the green part 
be exposed in greater or less degree. 

So plants have found it necessary to take upon them- 
selves certain adaptations by which all the cells doing 
chlorophyll work may get their proper share of the ligl)t 
which comes to the plant. These adaptations have affectejd 
the position and shape of the leaves and the length and 
position of the branches of the plant. It is not so essen- 
tial to know what the names are which are applied to tile 
leaf forms, as it is to know why the leaf has assumed that 
particular form, and reason for its form can nearly always 
be found when studying its light relation. 

135. Arrangement of leaves for light. — The arrange- 
ment of the leaves on the stem which has already been 
studied (see page 50) is an illustration of adaptation to 
light. In the case of opposite leaves, the pairs are placed 
at right angles to each other, so that no pair can directly 
shade the light from the ones below. In the alternate 
arrangement the leaves are also in vertical rows, but in 
this case the individual leaves in their adjustment form 
spirals, so that the third leaf is over the first, or the fifth, 




Fig. 14. A group of leaves, showing how branched leaves overtop each other without 
dangerous shading. It will be seen that the larger blades or less-branched leaves 
are towards the bottom of the group. 



From Coulter's Plant Relations. Copyright 1899, by D. Appleton & Co. 



ECOLOGY. CONTINUED 103 

seventh, thirteenth, and so on, is over the first, ample space 
for light being left between the ones that are directly over 
each other in the row. If the leaves upon a plant are 
narrow, there will usually be numerous vertical rows, but 
if they are broad the number of rows will be few. On the 
Twigs of the elm with its comparatively broad leaves only 
two rows are found, but the willows with narrow leaves 
have usually five rows on the stem. 

136. Division of leaf blade. — The division of the 
leaf blade is also of great importance in considering the 
light relation. Many plants, like the yarrow and dog 
fennel, have the leaves cut into innumerable divisions ; 
this is undoubtedly in order that the light may penetrate 
the whole plant. Compound leaves with small leaflets 
represent a similar manner in which some plants have 
solved the light problem. Plants with broad leaves we 
find have the lower petioles the longest, the ones above 
having successively shortened petioles, in order that each 
leaf may have light exposure. The common geranium 
will show this arrangement and if one looks down upon the 
top of the plant, the leaves will seem to be arranged in a 
pretty pattern, which is known as a leaf mosaic. 

Many plants show this mosaic arrangement when looked 
at from other points of view. Wall climbers, exposed to 
the light from but one side, usually show an interlocked 
layer of leaves, fully covering the wall, but not shutting 
off the light from each other. Sometimes none of the 
petioles of plants will-be of any considerable length, but 
will show the graded lengths, and the plant will form a 
close, compact body, known then as a rosette. The common 
houseleek is a tvue of this arrangement, and it is a matter 
of great interest to note the mathematical nicety with 
which its leaves are adjusted for light. 

137. Vertical leaves. — All of the features above men- 
tioned are found usually in connection with leaves that are 
placed horizontally on the stem. Some plants, however, 
do not hold their leaves in this position, but the petioles 
are so turned as to make the leaves vertical on the plant. 



104 HOME STUDY — BOTANY 

The hyacinth, tulip, iris and other common plants show 
this arrangement, as do also the compass plant, and rosin 
weed of the prairies, and the prickly lettuce of our road- 
sides. In this case the arrangement is such that the leaf 
will receive light more upon the edge than the surface of 
the blade, and is in the nature of a protection from too 
intense light. The leaves of the compass plant are often, 
but not accurately, arranged in a general north and south 
direction, the faces of the leaves thus receiving the morn- 
ing and evening light, but not the more intense light of 
noonday. 

138. Shapes of trees and light relation. — The effect 
produced upon the shape of trees by their adjustment to 
light conditions is often very striking. The evergreens 
are notably conical trees, that is, have conical outlines. 
This is due partly to the fact that the lower branches, 
beinp 1 most in danger of shading, have carried their leaves 
out farther to get the light, while the upper ones have 
not found it necessary to do so. Many trees, aside from 
the evergreens owe their particular shapes to this same 
feature, but it is often not quite so evident. Elms and 
maples have their lower branches the longest, but the 
branches do not assume great regularitv of position, as 
do those of the evergreens. In dense forests, where trees 
shade each other, the trunks often extend to great 
heights without bearing a single branch, for branches have 
been unable to live without the light, and only those at the 
extreme top of the tree have received sufficient illumina- 
tion for growth. 

139. Movement to light. — Any one having raised 
plants in a window garden will be aware of the fact that 
plants have power to make movements to adjust them- 
selves to the light. The common one-sided shape of the 
window garden plants is the result of the plant's struggle 
with unfavorable light conditions. If such a plant is 
turned around and left a short time, the leaves will invar- 
iably turn and readjust themselves for greater light expo- 



ECOLOGY, CONTINUED 105 

sure. This arrangement usually takes place within a 
remarkably short time. 

Plants growing in a state of nature are many of them 
unable to change their leaf positions at all, but some of 
them change them at intervals during the clay, in order 
to receive more or less light. Instances of this are shown 
in some compound leaflets, which turn their faces to the 
sun at some periods of the day, and the edge to it at other 
times. Many plants when night comes assume a position 
which is still called the sleep position. This is probably 
to prevent too rapid radiation of heat, rather than as a 
response to changing light conditions. The influence of 
light upon the position of the leaves and organs of a plant 
is known as lieliotro'pism. 

QUESTIONS 

1. What is pollination? What is its object? When 
and by whom was it proven that plants do not usually fer- 
tilize their own ovules ? 

2. What are the kinds of pollination ? Which is the 
more common method? Are flowers ever self pollinated? 
How is the violet pollinated ? What is cleistogamy ? 

3. What are the agents of pollination ? What plants 
are examples of wind pollinated plants ? What are the 
characteristics of wind pollinated flowers ? 

4. When animals are the agents of pollination, is the 
relation one-sided ? Why, in general, do flowers have 
showy corollas, nectar, and so on ? 

5. What adaptations for carrying pollen do insects 
have ? What are the characteristics of insect pollinated 
flowers ? How do flowers with regular corollas develop the 
element of attraction ? 

6. Do insects visit all flowers indiscriminately? 
What class of plants is most highly specialized from the 
standpoint of insect pollination ? 

7. What is a hybrid ? How do florists produce the 
great numbers of new varieties sent out by them ? What 
coi be said of the range of hybridization ? 



8. Bow do plants keep oil unweleo 

9. What are some : _r 



— 



id the gladiolus pollinated £ 

11. ~_~ plants need light What is meant by the 



_ T ~ C - 



: _ f:.Zr _-;-~t- - :_-~::„- ; ~t-~".;:„ - imrjj'-r-z. "~ 

the position of the leaves when growing naturally i What 
is the sleep of plants I What is heliotropism ? 



4. Corolla -{ 



OUTLINE FOR STUDY OF PLANT 

1. Dicotyledonous or Monocotyledonous? 
j Complete or Incomplete? 
\ Regular or Irregular? 

f a. Gamosepalous or b. Polysepalous ? 

| If a. describe its Tube and Border. 
3. Calyx •{ If i>. give Number and Shape of Sepals. 

j Is the Calyx Free or Adherent to the 

^ Ovary? 

fa. Gamopetalous or b. Pol>petalous? 
If a. describe its Tube and Border. 
If b. give Number and Shape of Tetals. 

L To What is it Attached? Color? 

f Number? United or Not? 

j If United, How? 
„ J To What Attached? 

j Are the Anthers Innate, Adnate or Ver- 
satile ? 

I Relative Length of the Filaments? 

f One or Many? 

I Simple or Compound? 

_,. „ j How many Cells has the Ovary? 

6. Pistil ~\ J J 

| kew or many Ovules? 

| Describe the Style and Stigma. 
iPlacentation? 

7. Inflo- ( Solitary or Clustered? 
rescence j Kind of Cluster? 



108 HOME STUDY -BOTANY 

T j Simple or Compound? 

I Venation? 

( a. Above or b. Underground? 
9. Stem i If a. Woody or Herbaceous? Direction? 



If b. Kind? 

10. Kind of Boot? 

11. Habit Study? 

(a. Cross or b. Self Pollinated? 
■< If a. Agent and Proofs? 
tl0n ( If b. Proofs? 
f Order? 
| Family? 
13. Classifi- j Genus? 
cation i Species? 

Scientific ISame? 
Common Name? 



INDEX 



Absence of nectar, 96. 
Absorption, 4, 47, 48, 57, 59. 
Abundance of pollen, 96. 
Action of frost, 50. 
Activity of protoplasm, 4, 

48. 
Adaptation, 80, 88, 90, 91, 

101. 
Adjustment to light, 103, 

104. 
Adnate attachment, 68. 
Adventitious buds, 31, 46. 
Aerial roots, 45. 
Age of trees, 38, 79. 
Agents of transference, 96. 
Alcohol, 11. 
Alga?, 5, 6, 8, 16. 
Alternate leaves, 50, 101. 
Alternation of generations, 

19, 22, 25. 
Amount of transpiration, 60. 
Angiosperms, 77, 79. 
Animals, 3, 8, 60, 92, 97. 
Annuals, 49. 
Anthers, 6Q. 
Antheridia, 21, 23, 25. 
Antitoxins, 16. 
Apetalous, 69. 
Appendages to seeds, 91. 
Aquatic hydrophytes, 89. 
Archegonia, 21, 23, 25. 



Archichlamydese, 81. 
Arrangement of buds, 29. 

43. ' 
Arrangement of leaves, 50, 

88, 101. 
Ascending axis, 45. 
Asexual spore, 5, 9, 19, 28. 
Assimilation, 58. 
Attractive coloring, 98. 
Axile placentae, 69. 
Axillary buds, 29. 

B 

Bacteria, 13. 
Bark, 36. 

Benefits of bacteria, 13. 
Biennials, 49. 
Bird pollination, 100. 
Birds as carriers, 92. 
Black mould. 9. 
Blade of leaf, 51, 61. 
Bloom on leaves, 53. 
Bracket fungus, 11. 
Branches, 28, 39, 71. 
Branchlets, 30. 
Bread making, 13. 
Breathing pores, 53. 
Brvophytes, 5. 
Buds, 21, 28, 29. 
Bud scales, 30, 42, 62. 
Bulbs, 42, 43. 



110 



INDEX 



c 



Calyx, 66, 68. 
Cambium layer, 38. 
Capsules, 23. 
Carbohydrates, 58. 
Carnivorous plants, 63. 
Carpels, 69. 

Carrion scented flowers, 99. 
Carrot, 45, 70. 
Catkin, 70, 78. . 
Cell division, 6, 21. 
Cells, 3, 4, 35, 38, 53. 
Cellulose, 4. 
Cereals, 80. 
Cheese bacteria, 14. 
Chlorophyll, 6, 8, 19, 54, 

57. ' 
Chloroplasts, 4, 7. 
Circinate, 26, 27. 
Classification, 81, 83. 
Cleistogamous flowers, 95. 
Climbing stems, 41, 42. 
Closed veining, 80. 
Clover, 14, 42, 47, 70. 
Club-mosses, 24. 
Clustered inflorescence, 70. 
Coal measures, 77. 
Cocci forms, 12, 13. 
Color of flowers, 71, 98. 
Compass plant, 104. 
Competition reduced, 87, 91. 
Complete flowers, 69. 
Compound leaves, 61, 103. 
Compound pistil, 69. 
Conifers, 40, 78. 
Conjugation, 7. 
Connective, 66. 



Constructive metabolism, 60. 
Cork, 36. 
Corolla, 66, 68. 
Cortex, 36, 46. 
Corymb, 70. 
Cotyledons, 39, 74, 79. 
Cross pollination, 95. 
Cryptogams, 5, 82. 
Cupules, 21. 
Cycads, 77, 78, 82. 
Cyme, 70. 
Cytoplasm, 4. 



D 



Dandelion, 45, 101. 
Deciduous, 49, 90. 
Delicacy of root hairs, 47. 
Descending axis, 45. 
Destructive metabolism, 60. 
Dicotyledons, 34, 40, 79, 81. 
Digestion, 59, 63. 
Dioecious, 70. 
Diseases, 8, 14. 
Dispersal of seeds, 74, 87, 

91. 
Dissimilarity of trees, 28. 
Dormant buds, 31. 
Duration of leaves, 49. 
Duration of roots, 49. 
Duration of stems, 41. 

E 

Ecological factors, S8. 
Ecology, 87, 95. 
Egg cell, 72. 
Elaborated sap, 40. 



INDEX 



111 



Elaters, 22, 23. 
Embryo, 72, 73. 

Embryo plant, 72. 
Endogens, 39. 
Energy secured, 59. 
Enmeshed alga?, 15. 
Epidermis, 43, 46, 53, 55, 

90. 
Erect stems, 41. 
Essential organs, TO. 
Evaporation regulated, 60. 
Evergreens, 50, 79, 104. 
Evolution of plants, 5, 90. 
Exogens, 39. 
Extent of roots, 48. 
Eyes of potato, 42. 



F 



Eall of leaves, 50. 
Families, 83. 
Fermentation, 11. 
Ferns, 24, 42. 
Fertilization, 21, 71, 72, 73, 

95. 
Fibrous roots, 46. 
Fibro-vascular svstem, 35, 

37. 
Filaments, 7, G6. 
Film moisture, 48. 



Fission of cell, 6. 
Fleshy roots, 45, 90. 
Floral envelopes, 70, 98. 
Flower dissection, C)(^. 
Flower grouping, 82. 
Flowering plants, 5, 82. 
Flowerless plants, 5, 82. 
Flowers before leaves, 96. 



Flytraps, 63. 

Foliage arrangement, 101 

Forms of bacteria, 12, 13. 

Free central placenta?, 69. 

Fronds, 26. 

Fruit, 34, 79. 

Fungi, 5, 8, 16. 

G 

Gametes, 5, 7, 19. 
Gametophores, 23. 
Gametophyte, 25. 
Gamosepalous, 68. 
Gemma?, 21. 
Genera, 83. 
Germination, 74. 
Girdling, 40. 
Gluten, 13. 
Grasses, 80. 
Groups of plants, 5. 
Growth of stems, 39. 
Guardian cells, 53, 60. 
Gymno sperms, 77. 

H 

Habits of stems, 41. 
Hairs, 63, 97, 100. 
Halophytes, 90. 
Harmful fungi, 11. 
Head, 70. 
Heart wood, 41. 
Heat, 88, 105. 
Heliotropism, 105. 
Herbaceous stems, 41. 
Holdfasts, 15. 
Honey, 99. 



112 



INDEX 



Horsetails, 24. 
Hosts, 15. 
Hybrids, 99. 
Hydrophytes, 89. 
Hyphse, 9. 
Hypocotyl, 71. 



Indusia, 26, 27. 
Inflorescence, 70. 
Innate attachment, 68. 
Insects and flowers, 70, 71, 

96, 97. 
Intercellular spaces, 51, 55, 

59. 
Internodes, 29. 
Irrigation, 89. 

K 

Kinds of buds, 30. 
Kinds of leaves, 61. 
Kinds of roots, 45. 
Kinds of stems, 31. 
Knots, 39. 



Laboratory work, 1. 
Lack of odor, 96. 
Latex, 100. 
Layers of bark, 36. 
Leaf exposure, 58, 60. 
Leaflets, 61, 103. ' 
Leaf mosaic, 103. 
Leaf scars, 28, 50. 
Leaves, 31, 19. 



Leguminosa?, 11, SI. 

Lenticels, 36. 

Lichens, 16. 

Light influencing shape, 

101. 
Light relation, 101, 101. 
Liverworts, 19. 
Lycopodium, 21. 

M 

Manufacture of food, 8. 
Marchantia, 19, 20. 
Material for studv, 1. 
Medulla, 36. 
Medullary rays, 37. 
Mesophytes, 89. 
Metabolism, -1, 60. 
Migration, 92. 
Mildews, 11. 
Modified leaves, 71. 
Moisture from leaves, 60. 
Monocotvledons, 31. 10, 79, 

80. 
Monoecious, 70. 
Monosepalous, 68. 
Mosaic arrangement, 103. 
Mosses, 22. 
Mould, 10. 

Movement to light, 101. 
Mucor, 9. 
Mushrooms, 10. 
Mycelium. 9, 10, 16. 

N 

Xaked buds, 30. 
Xaked seeds, 78. 



INDEX 



113 



Nectar, 96, 97, 100. 
Nectar glands, 99. 
Night flying insects, 98. 
Nitrogen fixation, 13. 
Nodes, 29. 
Nucleolus, 4. 
Nucleus, 4, 72. 
Number of stomata, 53. 
Nutrition, 16, 43, 45, 49. 

O 

Odors of flowers, 97, 98, 99. 
Oosphere, 21, 72. 
Oospore, 21, 23, 72. 
Orchids, 99. 
Orders, 83. 
Osmosis, 47, 91. 
Outline for study, 107. 
Ovary, 67, 82. 
Ovules, 67, 71, 78. 
Oxidation, 59. 



Palisade cells, 54, 55. 
Palmate branching, 61. 
Palms, 80. 

Parasites, 8, 10, 14, 16. 
Parenchyma, 35. 
Parietal placenta?, 69. 
Parts of a cell, 4. 
Parts of a leaf, 50. 
Parts of an embryo, 74. 
Parts of the stem, 34, 36, 

43. 
Path of sap, 40. 
Peat, 22. 



Perennials, 49. 
Perfect flower, 69. 
Perianth, 66. 
Persistent leaves, 50. 
Petals, 66, 68. 
Petiole, 50, 60. 
Phanerogams, 82. 
Photosyntax, 58. 
Photosynthesis, 58. 
Pileus, 10. 
Pines, 49, 77, 96. 
Pinnse, 26. 

Pinnate branching, 61. 
Pinnately veined, 55. 
Pistillate, 70, 78. 
Pistils, 67, 68. 
Pitcher plants, 63. 
Pith, 34, 36, 43. 
Placentae, 67, 69. 
Plant analysis, 81. 
Plants and animals, 97. 
Plant societies, 2, 87. 
Pleurococcus, 6. 
Plumule, 74. 
Pollen, 67, 78. 
Pollen grains, 67, 72, 73. 
Pollen tube, 72, 78. 
Pollination, 71, 75. 
Polysepalous, 68. 
Potato, 42. 
Primary roots, 45. 
Prostrate stems, 41. 
Protection, 16, 70, 99, 104. 
Proteids, 58, 63. 
Prothallia, 25, 26. 
Protonema, 23. 
Protoplasm, 3, 4, 48, 58. 
Pteridophytes, 5, 24. 



114 



:nzzx 



PufibaHs, 10, 11. 
Purpose of color, 98. 

B 

Raceme, 70. 

Rain. ": 

Range of hybridization, 99. 

Raspberr" -i. 

Ratio pollen grains to seeds, 

:?. _ 

Receptacle, 68. 
Redwoods, 79. 
Regular flower, 69. 
Reproduction, i, 10, 19. il. 

_.T-piration. 58 3 " . 
RestoTiiig the soil, 11. 
Reversion, 71. 
Ehizoids, i\ %\, 23. 

Ribs, 55. 

Ring's of growth. ■'" ~ 

Rivalry, 91. 

Root cap, 46. 

Root hairs. - . -7 

Rootstoeks. -i. 

I. • :: ?ysTems. 4S. 

~ : ~ mbercles, 1-4. 

R ---- habit. 23. 103. 

Rnsts. 11. 

B 

- p, 4a 

Saprophytes, S, 10. 

Sapwood. 41. 
Scale leaves, 
Sea wee Is, 8. 



Secondary roots, 15. 
- - - \ ". 
^t-:_:i_t-_;.. i-. 
Selective action, 4^ 48. 
>r_z ::•■: __i:_:.7:::i. 'I ' . 
Sensation in plants, 3, 1, 63. 
Sepals, 66. 
Sequoias, 79. 
Sessile, 51. 

Sex elements. ". 7 19. 
Sexz.i_ -"::-?. ."•. ::, 
Shapes of trees, 101. 
Showers of sulphur, 96. 
Simple leaves, 61. 
Simple pistil, 69. 
Size of stomata, 53. 
Sleep position, 105. 
m^-.\-~. 11. 
Soil -:.--. 4^. SS. 
Solitary inflorescence, 70. 
S:ri. i 

ies, -3. 



Si 



, 21 



28, 



77. 



Spirogyra. 7. 



25. 



23. 



on, i 1 



R T 



Starchy i 
S I 3ns, 34. 

S'lilTLf'.. ' ~ 

— -r. 10. 



". 4: .;-.:". 74. 



INDEX 



115 



Stipules, 51. 

Stomata, 20, 53, 55, 60. 

Storage of food, 10, 13, 15, 

19, 03, 72, 71. 
Structure of a bud, 29. 
Structure of leaves, 53. 
Structure of roots, 16. 
Struggle for existence, 22, 

88, 91. 
Style, 67. 
Sunlight, 57, 101. 
Sympetalge, 81. 



T 



Tap roots, 45. 
Temperature, 3, 37, 88, 90. 
Tendrils, 42, 51, 62. 
Tentacles, 63. 
Terminal buds, 29. 
Testa, 73. 
Tkallophytes, 5. 
Thallus, 0, 20, 21, 25. 
Toadstools, 10. 
Toxins, 10. 

Transpiration, 00, 90. 
Transportation of seeds, 92. 
Tree planting bv chance, 92. 
Trees, 28, 47. 
Tropophytes, 89, 90. 
Tubercles, 14. 
Tubers, 42, 43, 63. 
Tumbleweeds, 91. 



U 



Unwelcome visitors, 99. 

V 

Varieties, 83, 99. 
Variation in flowers, 69, 98. 
Variation in roots, 16. 
Vascular system, 24. 
Vegetables, 80. 
Vegetative multiplication, 6, 

22. 
Veins, 26, 55. 
Venation, 55. 
Venus's flytrap, 63. 
Vernation, 31. 
Versatile attachment, 68. 
Vertical leaves, 103. 
\ 



mes, 77. 



Umbel, 70. 



Unit of structure, 3. 



Violet, 62, 83, 95. 
Vitality of cells, 38. 
Vitality of seeds, 74. 

W 

Wall climbers, 103. 
Water, 4, 13, 15, 19, 21, 31, 

40, 47, 88. 
Water pollinated flowers, 

100. 
Wheat roots, 49. 
Wheat rust, 11. 
Whorled arrangement, 29. 
Wind, 70, 88. 
Wind pollination, 96. 
Winter buds, 30. 
Woody stems, 41. 
Woody tissue, 34, 36, 43. 
Work of the leaf, 57. 



116 



X 



Xerophytes, 89, 90. 

Y 
Yeast plant, 11, 90. 



INDEX 

Yucca, 96. 
Zygospore, 7. 



NOTES 117 



These blank pages are supplied to afford a place for 
the preservation of items of interest gathered from time 
to time by the student in his study. 



118 NOTES 



SEP 



SEP 13 1902 



SEP. 15 190? 



^»^ 









■»/ f. T MUiZ? 



